Boatboy,
I agree with much of what has already been said so I won't repeat it all but I will highlight a couple things.
Borrow and test anything you can to try. The AI that assisted with my open water class let me use his wife's Diva BCD in the pool so I could experience the difference. Now I wouldn't own anything else. My AOW instructor was big on showing you how different regulators breathed at depth so he had us try each others when we got down to about 90 feet. This is how I decided the ScubaPro MK20-G250 was for me.
Buy used when it makes sense and you knew the previous owner took good care of the item. Divers are constantly upgrading to new "toys". Find somebody that is alittle ahead of you and offer to pick up their cast offs! I got my MX-10 camera because a fellow dive club member was moving up to an nicer model. She didn't say she was going to sell it but when she was showing off her new camera, I asked what she was going to do with her old one. We are both happy with the sale!
Join a dive club or attend a lake clean up where you can meet divers from many dive shops. This will increase your exposure to different gear that you might not even know is out there. If you see someone has a pair of fins you are interested in, ask them how they like them. I have traded fins, dive lights and other accessory gear with people for a dive or two to test it out. Divers tend to be a pretty social bunch.
Realize that diveshops sell only certain brands of gear. The owner might really like ScubaPro and think it is a good brand but if there is already a ScubaPro shop in the market, the manufacturer will not let another shop carry it. I know that happens here in KC. Dive shops also require their instructors, dive masters and other "shop staff" to use only gear they sell when working with students. I am a divemaster's wife and I have even been given a hard time by our LDS because my have an assortment of gear and wear gear that the shop does not sell around students. I take this in a good natured way because I am not a paid advertisement for the shop like my husband is but realize that while your instructor, divemaster and shop owner may be friendly, they also have an angle.
Best of luck in all your diving adventures,
KC_Scubabunny