Looking for a Treadmill

I'm starting to prepare for receiving my service dog in a few months - should be by the end of the year - and one thing I need is a treadmill. My dog is about 18 months old and pretty energetic. I plan to walk him a couple times a day but he will need more exercise than that and I am not able to take a dog for a run. The trainer suggested getting him a treadmill, which sounds funny to me, but I'm told he enjoys walking/running on a treadmill. So if anyone has an old treadmill they don't use anymore, or knows anyone that has one, please let me know.