I know most people are biased against products made in China but I've been using some from an ebay seller http://stores.ebay.com/e-MadeinCHN for a while now, they work great (haven't tried serial yet, just controls).
They have great customer service and I'm pretty sure they are FCC approved. They have a website at http://www.e-madeinchn.com/
Much cheaper than most wireless modules I've found.
hope this helps
Bookmarks