My soaring bill so far this year is about $2800 (club + national membership, glider block time, tows) for about 60 hours.
Renting a Citabria gets close to $200/hr these days in Canada.
I'll disagree with IFMU's
You never have to worry about engine failure in a glider
It can be very inconvenient if the towplane engine quits or the rope breaks, or the winch has a problem
Actually gliders are pretty much solar powered. When the lift quits, you'd better be close enough to the field or you will shortly be doing your very first outlanding like I did