If you really are going to buy a large variety and many different sizes, then I would say a trip to the SF or LA area would be appropriate. If you decide to hit SF there are multiple REI, Sierra Designs, The North Face (outlet and retail), Marmot, and for Maxpedition there is Tadgear.com (store in SF). In addition to that there are many other outdoor gear stores.

Make a weekend out of it. If you are buying that much gear and don't know what you want, trying them out first hand will be best. Bring your own sandbags or 2 liter water bottles for loading up packs. Most REIs have these for trying gear out while actually carrying weight, but many other stores don't.

It's your $$$ <img src="/images/graemlins/grin.gif" alt="" />