Free: Contests & Raffles.
Last year I had a few of them making hills in my yard. I busted out the claw traps but for whatever reason couldn't catch them. We took some of the big good quality road flares......lit them, stuffed them down the hole then I put a bucket over the hole. Every now and then there'd be a smoke leak...just took some dirt and covered up the leak. Let that flare burn itself out...haven't seen a mole since. You can buy the mole/gopher/pest smoke bombs at the hardware store too but the road flares seem to have a lot more horsepower.
Get your hands on 5-6' of alum flex pipe slightly larger than the exhaust pipe of your lawn mower. Pick up a small roll of metal duct tape, the shiney silver stuff. Connect the flex to the exhaust pipe of the mower. Clean out the top of the mole hill to expose the tunnel. Shove the pipe in 6" to a foot and pack the mole hill dirt around the hose. Start the mower and leave it partially choked. Let her idle for good half hour or more.