That wouldn't work too well as the glass is more than likely too thick. You'd have to sit there for 5 minutes just heating the glass up. THC also vaporizes at 220degC, and using a lighter is not a good way to ensure that you are reaching that temp.. If anything, it goes much higher than that and you'll end up burning it anyways.

If you want a cheapo vape., just make one out of a lightbulb, but those can be hard to know if you're burning or not either.