eh, i wouldn't cheap out on memory cards...might end up corrupting your files unexpectedly, especially before you upload them...now that would suck.
but if you're ever in the market to buy electronics, i usually use
http://www.pricegrabber.com
basically another search engine, but a trusted site...ordered from the vendors on there several times..heck, just ordered me 2 microSD cards for only 22 bucks each.