You can get a telo for $180 - 200. Then your first year is free (make sure to opt out of premium if you don't want it or there will be a small charge per month -- under $12 or so). Then your second and each subsequent year is something ridiculously low like $12 per year. It's hard to beat.
Paying the cable company $50 a month for VoIP is for fools. Vonage only sounds slightly better.