So embedded Ethernet is finally getting cheaper.
If you can figure out how it works, the Wiznet NM7010A-LF can be had for $22.
On the other hand, Lantronix now has the Xport Direct, a slightly scaled back Xport for $36. Unfortunately, it is on 2mm headers, while standard breadboards are 0.1 inch, so you'll have to get creative to make use of it (wire-wrap?)
And there is the Lantonix MatchPort is a wireless b/g interface for $75.