I would love to get as big of a micro SD card as possible for a great price for my Blackberry, can't have enough memory, you'll need that space sooner or later.
Check out pricewatch.com. They'll point you to some good deals. About a month ago, I got a 4gb Kingston Micro SDHC card with 2 standard SD adapters, a mini adapter and a micro keychain adapter for 12 bucks shipped.
Posted from my CrackBerry at wapforums.crackberry.com
I got several 8GB Sandisk cards off ebay for around $20 a piece. I also purchased six 2GB cards from woot.com for less than $25 shipped.
I found out this weekend that my wife's new Canon XSi digital SLR will run through a 2GB card in no time at 3.5 fps so I purchsed her several of the 8GB cards. But man, talk about catching some awesome action shots!!
I have so also recommend NewEgg, but they don't have a ton of the bigger ones. If you look for free shipping, you can find deals. I got a pair of 2Gb ones for my wife and daughter and spend $13.98 total.
NewEgg is one of the top-trusted companies on the Net. I order from them all the time, and their customer service is amazing.