There isn't any 'generic' RAM types, as you seem to be implying. Each motherboard requires a specific type of RAM; you can't mix and match. The type that MacBooks and MacBook Pros use is SO-DIMM 667 Mhz PC2-5300 DDR2 SDRAM. The manufacturer of the RAM shouldn't affect its compatibility however, and so you can get relatively cheap third-party RAM for the MacBook.
I got my RAM off of NewEgg:
http://www.newegg.com/product/product.aspx?item=N82E16820231069
John A
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