Unboxed one for $130:

http://cgi.ebay.com/Dreamcast-Broadb...3286.m63.l1177

Looks like the recent price for a fully boxed adapter has been $199. The last sales in March were $199, $199, and $159 for the Japanese versions from the same Seller. He sold them for $159 in February then bumped up the price to $199 in March and sold two more. A fully boxed US version went for $239.

If you want to know what's it's worth today I'd say $199. Next month....or 6 months from now...who knows?