Whilst I consider gliding a fine and excellent form of aviation, I gave up trying that as a route because the early training is actually more expensive than powered on an hourly basis.
There is certainly some truth to this, and I think that a large grain of salt should be taken with claims that gliding/soaring is much cheaper than powered flying. Sometimes it's cheaper, sometimes it's more expensive ... there are quite a few variables.
I also agree with Bose-X that learning to fly gliders is probably an inefficient first step for someone who aspires to become a commercial airplane pilot. Personally I enjoy the social aspects that come from all of the waiting around of the soaring world, but it is not for everyone, particularly someone with limited time.
Much of my own flying is inexpensive, because I fly my gliding club towplane and instruct in gliders: both are unpaid positions, but offer 'free' flying. But of course there really is no such thing as a free lunch. I don't mind occasionally paying to rent an aircraft, as the freedom to go off where you want, when you want, is priceless.