Just got certified and I'm looking for my first gear purchase.
Problem is I'm also buying a set for my wife and my 14 year old son.
I don't want to buy new in case they don't like it very much.
Lot's of used gear around here to choose from. I have a couple of questions.
1. How important is it to buy the same brand that our local shop deals in? (Tusa, Aqua lung)
The issue you have is getting service. Most shops will not service a brand that they do no carry (it's likely they do not have access to parts). By sticking with a brand the local shop carries it makes your life easier. Plus they are more motivated to order parts if they are a dealer as opposed to hunting down a supplyer of parts they do not have ready access to.
2. Are parts for other brands not available to them?
That is very likely, scuba manufs are real picky about dealing with only their "authoized dealers".
3. Can I order parts and fix things myself?
Depending on the brand and model you may or maynot find them available. While I am a big DIY fan, you still need to understand how to service your own equipment. Looking for a brand/model you can do yourself down the road is not a bad idea but I would suggest you leave the service to the pros until you have some diving experience and time to learn to work on the gear. We have a very active DIY section on this board, I would encourage you to follow the threads even if you don't have that kind of gear, you will learn a lot hearing what others are doing.
4. When I go to look at regulators and BC's what do I look for?
Brand, model, fit and overall condition are your main concerns. Avoid brands or models that are from the smaller brands or brands you can not find dealers for. Dacor is a good example. In the day they made good regs but they are now out of business and parts are diffcult to find. While there are a lot of good brands on the market, Scubapro and Aqualung (aka US Divers) are the better bets if you are looking at older regs, most of their regs from the last 30 years or so you can still get parts for......assuming your LSD wants to. When looking at used regs, take a careful look at the hoses. 3 new hoses will set you back over $100. Add that to the $120-150 service you will need and the price jumps a lot. I am not saying used is a bad investment, far from it but you do need to keep the service cost in mind.
BCs are not as big a deal. Blow it up orally and see if it holds air for an hour or 2, if it does and it looks in good mechanical shape (fading is not a big deal) you are good to go. If it doesn't check to see if you can find the leak, small leaks around dump valves are common and often times good cleaning will solve that. No reason to pass on an otherwise good BC just because of a dirty valve.
I will have to disagree with shady on the BP. While great BCs, they are not the be all, end all theirs fans make them out to be. They are a royal pain in the rear to adjust and rarely are less expensive than a new mid range BC. While they are widely adjustable, the benefit of that is must less than you are lead to believe. Most modern BCs will adjust over a fairly wide range (and much easier). Unless you are swapping the BC around between several family member that widely vary in sizes it makes little difference that the BC is "infinitely adjustable". Even with growing kids, a used BC can be used for several years and resold for most, if not all your original purchase price (assuming you got a good deal to begin with). Between regs and BC, your best saving money oppertunity is with the BC. Often times you can find a quite servicable BC for under $50.