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) 2. Are parts for other brands not available to them? 3. Can I order parts and fix things myself? 4. When I go to look at regulators and BC's what do I look for?