newbie diver,
Welcome to diving! Yes it's expensive, but in my opinion, so much more rewarding than Medal of Honor, Call of Duty, Doom, Mech Warrior, etc.
Diving puts you in touch with the real world, life, the pulse of the planet, not some made up, digital escapism.
Not to say I don't enjoy the occasional couple of hours spent playing video games, but I sure get more out of watching what student divers get out of diving, my kids eyes when they see new creatures and my own enjoyment from seeing a 100 lb grouper, 5' barracuda, or 8' shark thats 2' away. There's a thrill no video game will ever provide.
As you know from taking your PADI course, you need to have mask, snorkel, fins, booties. These don't need to be break-the-bank, best-of-the-best, high expense items, but they are not the things you buy at Wal Mart either. (Don't buy the mask, snorkel, fins you find at Wal Mart, KMart, etc. They are not designed for the pressures, stresses of diving).
This may turn out to be long, but I'm trying to help. In the end you will have to decide. But you've already invested in the training, I think you should give it a year after that and then decide.
One thing that may hepl is if you fill in your profile so we know where you are, know more about you, what prompted you to take up diving, what your goals are. If we know where you live, someone here may be able to point you in a direction of a good, reputable source if the LDS (Local Dive Shop) is not willing to work with you on pricing.
Here we go, but remember these are only recommendations based on my experience, preferences. Take the advice you get from me and others, massage it, fit it to your own wants, needs and decide.
One point: Don't use the LDS as a "fitting room" then go buy online. The LDS is there to serve customers and they are trying to make a living. Put yourself in their position.
Mask - This need to fit your face. You should get properly fit at your LDS. Each persons face is different and your mask needs to properl seal. If you have tried a mask from a friend that fits, then you could buy online. Masks for scuba diving are designed to withstand the water pressure at depth and not have the lens pop out of the frame and attempt to become contacts.
Snorkel - Multiple options as to size, style, features. Do you want one that has valves that make it a "dry" breather? Standard "J" shape? Will you be using it for snorkeling also, in this case you may want a dry breather.
Fins - Choices galore. IF you are going to be diving warm waters only, then you can go with the "full foot" design where you won't wear booties. Generally designed for snorkeling, some of these are not designed for propelling you AND scuba gear through the water. They will cause you to use more energy and air, plus they may crack or break. If you go this route, make sure they are designed for scuba also.
Open-heel fins require booties and tend to be a bit more expensive. But they are usually easier to get on and off, can be used for diving and snorkeling, warm or cold water. Probably the overwhelming choice for divers.
Then it comes down to style. Do you want traditional "blade" style or split? There are other options, but usually these are the two main choices.
Fins can be bought used, online, at the LDS. You can usually borrow some from the LDS to "try before you buy". Some LDS include the use of mask, snorkel, fins in their classes at least for the Confined Water (pool) training.
Booties - The neoprene boots of course. These need to fit snug but not tight, be of an appropriate thickness for the climate you'll be diving. Prices vary based on manufacturer, type of neoprene, sole construction, zippered or non.
This basic package of mask, snorkel, fins booties, can be had at an LDS for under $200. That should not be difficult to find if the LDS is reasonable. Most shops I know have basic packages for around $175. Buying as a package generally gets you a discount and you can sometimes even get a break on that. Some LDS will offer a discount if you're taking their course. Talk to them and see if they are willing to work with you.
Now the big ticket items.
Don't buy them yet. There are some things you can get from the internet, some things I strongly recommend buying from your LDS.
However, what I recommend to any new diver, I even recommended this when I was part owner of a dive shop, get experience first, equipment second. You need to ensure that diving is something that you will do enough to make the investment worthwhile.
You have already expressed concern as to whether or not you should continue due to cost. That tells me that you should only invest in the minimum required gear at this point. Remember, mask, snorkel, fins, booties can be used for snorkeling even if you decide never to dive again.
Additionally, at this point you don't even know that you will be able to dive, if you've not completed your open water dives. Some people run into issues with equalization, phobias that prevent them from diving.
Another factor is that you're not even aware of what all types of diving there are. Will you be purely recreational or want to get into technical diving? That has an impact on the type(s) of some of the gear.
Finish your OW training. Then if all is well and you want to continue diving, rent for a while. Talk with your LDS about your concerns of cost. Ask them if your rental fee or part of it can be applied towards the purchase price. Tell them you're not sure about gear configuration and would like to try a couple of different setups. Ask if you can use their pool to try gear in.
Keep in mind that some of the major factors that help make diving enjoyable are feeling safe, comfortable in the fit of your gear, confident in the quality, and satified that your paid what you wanted. You don't want to rush into or be pressured into a purchase that will lead to buyers remorse.
Your LDS should be willing to work with you to build a long term relationship. There needs to be mutual respect both ways in order for it to be successful.
Ask if they will be having any beginning or end of season sales. Usually dive shop periodically sell old (usually 1-3 years) equipment that has been in their student/rental programs. If you find something online that your LDS carries, ask if they can match the online price. Maybe they can't but maybe they can come close. It never hurts to ask.
Ask about package pricing. Discounts can be significant when equipment is priced in a package.
Given all this, the one piece of eqipment I most strongly recommend buying from your LDS is the regulator. This is life support above all the others and needs to be properly maintained. Some manufacturers will not honor the warranty if it not purchased through an authorized dealer. That can lead to more expensive service and reapir costs in the long run.
Above all, don't hesitate to ask questions, either here or the LDS. Scubaboard members are willing to help, provide input and be a sounding board. There is a phenominal amount of knowledge, experience and opinions here.
Hope this helps.