Currently Being ModeratedNov 7, 2012 8:05 PM (in response to bm122021)
One way to get plenty more loops and instruments would be to buy MainStage 2. This program will install all five JamPacks in your System Library, so that the loops and instruments are available to GarageBand. You can buy MainStage 2 at the App Store at a price that is far less than the price for a single Jam Pack.
Also look at the FAQ: hangTime's Bullets &Bones site has links to free loops: