The new etrex basic is WAAS enabled.
Data cables for the etrex line can be had on ebay for around $12 dollars including shipping, look here. That's where I got the cable for my 76, and it's as good a unit as what Garmin sells. They're drunk if they think I'm paying $40 for a serial cable.
Used etrex basics can be found well below $50 for just the unit, but that likely won't be one of the newer WAAS enabled unit. For that it will run you $90+. Wal Mart has this model on sale a lot.
I still have my trusty old etrex yellow, can't bring myself to part with it. No mapping, no cursor, very few icons, but it gets the job done. True, it loses the signal in heavy cover, but combined with a Bushnell digital compass I can back up to my last good signal and take a sight bearing.
Trust me, you'll do fine with whatever you decide.