My quick tips would be:
- don't buy anything right away, rent and borrow for a while
- when you know what you want to get, try eBay first - a small scratch is a big saving
- if you can't find it on eBay, try leisurepro.com (check "used gear" first)
- the one exception I make to rules 2 and 3 is for wetsuits, but maybe that is just me
- if/when you get a computer, I suggest getting a cheap one first, and wait a while before getting a fancy one (if you get a fancy one at all)
- scuba divers tend to be hugely brand loyal, so don't expect many honest opinions that are worth anything
- never buy "the latest thing"; to quote a pilot friend: better to be in a plane that has crossed the Atlantic 200 times than on a maiden voyage. Lots of new products do not become successes