http://en.wikipedia.org/wiki/WRT54G
this shows what revisions have what ammount of memory and flash space, i suggest the WRT54GS v1.0 to 3.0, but uhh, with prices the way they are maybe u should just up the budget a little and get an avila gateworks router, it wouldnt be that much more and youd get twice the router, a router, if 100% stable and 100% fast, is something that can last you your whole life, especialy with an avila gateworks router, since when you need to upgrade your wifi setup, you would just get a new miniPCI wifi card, also since you dont have an internal switch, when you need to upgrade your internal lan, you just get a new switch... i guess if you ever needed more than 100mbit internet [or 1gbit internet depending on what model you go with] you might wanna upgrade it someday... i think i could prolly live with 100mbit internet my whole life.... heh im gonna regret saying that i know it :?
my router is a WRT54G v2.0 [one of the ones with 32bit ram]
i would say, dont get anything with less than 32mb ram, and if you can help it get something with 8mb flash space, mine only has 4 so i cant run alot of extra stuff without modding it, i think i would give alot to be able to run an eggdrop or something on it :?
oh and also, last time i checked, a WRT54G with 4mb flash and 16mb ram costed around 70 dollars, those are the same as a WRT54GL
a WRT54GS with 32mb ram, and 8mb flash space, that was worth about 130-150
that was used ebay values about... half a year ago or so? since they are worth so much the early revisions of the WRT54GS sometimes would get sold on ebay as that, but then when you got them they would be a newer revision with less memory and flash space, it was a real headach