have you thought about trying a linksys WAP54G or WRT54g . both of these have open source firmware upgrades from
www.sveasoft.com I have the wrt54g and you can increase the output of the antennas from its standard 34mw up to 84mw's. go to their forums and read more about the firmware if you're interested, but with the upgrade in firmware its a really powerful sub 100$ router/ap