George, Seeed is a pretty big name. I ordered an RFID reader and tags from them awhile back, and it worked great and was the cheapest solution I could find. It might take awhile to get things, but they are well known and actually work with a lot of other OSHW vendors like Dangerous Prototypes. Their documentation wikis are pretty good too.
I've heard of iTead, but haven't ordered from them before. I haven't heard anything bad about them, though.