+1 First thing I do is toss the retainer, except for Ashtabula cranks (old heavy Schwinns) and on headsets (loose balls are kind of a pain there to install). Headset is full minus two, everything else is full minus one. Typical front wheel 10 per side 3/16 inch, rear wheel nine per side 1/4 inch, bb 11 per side 1/4 inch. There are exceptions!

As far as rewarding a particular shop or site, start with your local LBS. Feel them out for a shop that will spend some time explaining stuff to you, do minor jobs without delay, and reward them for their exceptional service. Chances are, you need to focus on one shop, as you won't be buying enough to build a reputation with several.

Sheldon Brown on bb loose ball bearings.

http://sheldonbrown.com/tooltips/bbadj.html

FWIW: I buy pretty much all of my consumables on line, but I work on bikes every week. I tend to get loose ball bearings in bulk, added to an order with one of a variety of on line retailers, to fill out an order/satisfy free shipping requirement, or whatever. I find loose screws to be a handy site, but expensive. I haven't bought from them in years.

Paying the premium for buying at the LBS would add up quickly. But if I was just maintaining the family fleet, I would just go the LBS route.