Congrats on your certification!
Now the fun part begins.
Here are a few questions for you.
What does your dive buddy dive? What does the people in your dive club dive? What are your dive plans for the next 50 dives? I am asking you this because the more information you have the better decisions you will make. We can say exactly what works for us and what we did but, we might not exactly have the same plan, goals, or money as you.
Here is what I did. I did a lot of reading. Looked a review. Looked at different set ups and what people were using. The first set of regulators I purchased were used form Craig's List. It was a scuba pro mk 20 recreational octo set and, it came with a simple air computer.
so...
I paid 150 I think for the set. Sent it to my LDS to have it serviced. I think I paid 50$ per stage for servicing. That is one first stage and two second stages. for 150$ total. It worked very well with out issues so, 300$ for ready to use cost. I still have it and let people borrow it that need it. I sold the computer for 50$
I still kept doing research and looking here and there for information. I also wanted to move to a long hose/necklace configuration because it is the configuration my dive buddy/mentor dove and I read a lot about it and it made a lot of sense to me. It was close to Christmas and Dive Rite In Scuba had a Christmas sale on Hog regulators. I wanted them because they required service only every two years and LATER after I am TRAINED I could service them my self. I also want to say that I purchases those on sale brand new with warranty for something like 500$ I mostly do warm water diving but, paid the extra 10 bucks to get the cold water feature. I felt that more people would want that if I wanted to sell it and what is 10 bucks.
I would say you can find good gear for sale used but, you have to know what you are looking at and what it is work (what you could sell it for) if you need to.
Hope that helps!
Bait