Wait wait wait, before you buy stuff, do you have a "soundfont" player? If you do, try looking around the net for sites like http://www.hammersound.net/ or something of the like. The file extensions are usually .sf2 but some may be .sfARK
After downloading them (assuming you have a soundfont player) shove them in any folder, prefferably near the rest of your music generators and whatnot, then open it via the soundfont player plug in, et voila free sounds. However, if its .sfARK look up google for a program called Alive (or its equivalent)so that you can decompress the sfARK file and use it in your soundfont thingy.
Hope that helped