Regulators: do not save money here. If you have a budget, cut half of it to buy the best you can. It is better to have a mediocre drysuit/wetsuit and fins than a mediocre regulator: it does not matter what kind of diving you are doing;
Disagree. Most new divers should start with regulators that are (a) affordable that works reliably and (b) which can be serviced.
The problem with the advice is when you're a brand-new diver, a lot of this gear is confusing, and you don't know what you're shopping for, and it's all too easy to spend a bunch of money on regulators based on bad advice from a dive-shop, and get something that is actually not suitable for whatever diving you intend to do long term. It's much better to simply start with something that works, doesn't break the bank, and only when you out-grow that initial set, and are ready for more advanced dives, start looking into more fancy regulators. Second, dive-shops will absolutely love to sell brand new divers regulators they can't afford and don't need.
Computer: think about buying a multigas computer…by now you can find it at the same price of an air/nitrox computer (e.g. Garmin G1) but it will serve you over the long period;
Again, disagree. Start with something that works and does the job. When you are more experienced, you'll likely out-grow any computer you buy as a beginner. You really don't need anything fancy as a beginner. The main thing I found useful as a beginner was the ability to upload my dive-log to a computer or cell-phone for storage.
When you're actually ready for more advanced dives, whatever computer you bought will probably get buried under a pile of scuba-equipment you forgot you had. If you're smart, you'll remember to sell it (speaking of which, computers around the $300 mark new are extremely cheap on the used market). At that point, maybe you'll want a fancy $1000 computer with Air integration, a really nice screen, and a bunch of cool features. If you spent $50 instead of $450, you'd have that extra $400 saved up for a much nicer computer.
Multi use equipment: although 90% of your equipment will be for scuba only, you can still buy few pieces of your configuration that will serve you in other hobbies or everyday life
Sure, when you happen to come across multi-use stuff, it's nice, but I'd say multi-use is generally a bad principle to follow.
1) Your list of multi-use equipment will generally be EXTREMELY tiny.
2) Multi-use creates complications. For example, tools. Scuba-tools are generally more compact and more specifically applicable to scuba-equipment by having the right sizes, and not a bunch of nonsense I don't need. 2b) Much of my scuba-tools and save-a-dive kit has some non-dive application, HOWEVER, I almost never go digging through my save-a-dive box for a tool because later, when I'm out diving, I might discover I forgot to put that tool back in my kit.
3) The other problem with multi-use equipment, is you end up spending more, for items that are less suitable for either purpose. That's very true of tools as I mentioned in point-2 above; carrying an entire set of hex-wrenches is a little excessive. Instead, you can get something like the XS Scuba Start Tool, which has all the right sizes, is stainless-steel (very rust-resistant), and in a tiny package can cover about 90% of my scuba-tool needs in a pinch.
I've been guilty of this myself and had to grow out of it, but the pursuit of trying to save money in this kind of way can actually end up costing you a lot more money. It's not a universal rule of course, but this is an area to be cautious around.
