You can pick up a cheap one just about anywhere, Wal-Mart, Coin/Stamp stores and shows. I have a 16X jewelers loupe for quick and detailed portability, I just picked up a
LIGHTED POCKET MAGNIFIER, 4X, W/8X BIFOCAL for $5

http://electro-optix.com/magpocket.html

again its functional, portable and you don't lose sleep over where you put it down.

For home use, I would recommend you spend a little more...

http://www.keysan.com/big/piclled0440.html

for about $100 you get a great 5" lens with a ring light, saves the eyes, and keeps the hands free.
you can go much pricier but between those three I have found it serves most of my chip and coin needs.