Actually you can test drive a lot of gear by going to your local dive shop. They will also be able to service what they sell and be more than happy to help you choose what to buy.

Or you can do what I do and buy most everything from internet vendors like Leisure Pro and on eBay. I do the research before every important purchase, both gear and vendor. I make sure that in the case of new gear I will get the manufacturer's warranty and that someone in the area can repair it. After that, it all comes down to price.

I'm sure I'll get flamed for saying this by people who insist on buying everything from the local shop. C'est la vie.

When you buy from your local shop, you try it on before you put your money down.  Shops typically offer service deals for your gear ( free labor on annual service, repair service through the manufacturer in cases of a major screw up).  Gear purchased at your local shop also carries the manufacturers warranty.  The internet is "buyer berware."   You can get some great bargains on the internet, but you only need to get cheated once. 

Gear recommendations depend upon the type of diving you plan to do.  Are you diving locally or are you going to dive on trips to warm water locations.  You need to find BCD's that will fit comfortably with the suit you wear.  will it have enough lift.  Your local shop should be able to answer these questions.  A regulator should be comfortable for your mouth and easy breathing.  Do you want a dive computer?  You should be comfortable with its operation.  Many shops will give you a free computer dive course with the purchase of a computer.  If no computer, the the gauges should be easy to read with your mask on.  Put the entire package together and try it on.  Can you find everything easily?  Once you purchase your new gear, I would strongly recommend going diving somewhere you are comfortable and get acclimated to your gear and the location of everything.  Don't forget enough clips to keep everything neat and organized on your BC.  Even the most basic gear should last a very long time if you take care of it.

Al

I purchased some gear online from a retailer that no longer exists. I was assured by the company through email communication that the manufacturers lifetime warranty was in force and honored by the online retailer. That turned out to be false advertising. When I had a regulator free flow I had to send it back to the online company at my expense. They charged me to fix it and to ship it. I also believe that in the future I would like to have the advise of an instructor to help me decide on my gear purchases. Because I was trying to save alittle money I now have to live with gear that I don't really like and can't get fixed under waranty because I listened to some other individuals online recommendations. Let's face it very few recreational divers really know anything about fit and function.

In my opinion...

Buying from a store or online can be gray area.

The life saving equipment should be bought from a store/instructor to ensure it's in prefect condition. Also you want a place to service it.

Simple stuff like gear bags can be bought anywhere. If the strap breaks, oh well...you'll be OK. If I can buy a bag online at 1/2 the price, why wouldn't I?

My 2 cents.