i would get the adata 4gb class 6 microsd from newegg.com
its only 36 with free shipping( out of stock ATM)
its really fast, Avg read speed was 20mbs and random access was .7, thats faster reading than my kingston 2gb japanese, its 18mbs and random access .9
it all depends on what you need and want.
of course money is also a factor.