In floor heat isn't that expensive. The tubing isn't all that expensive, and your heat source can be a water heater (preferably gas). One of my buddies has that setup and a lot of the time his shop building is too hot, even when it's way below freezing. You don't need an expensive boiler to run it. I'd get it priced out for comparison. But down there you can probably heat it with a camp stove in the middle of the floor.
You probably don't care about finishes, so the electrical and lighting can be surface mounted and done after the building shell is completed (as long as you have the stub-ins for the service - and that can even be overhead or outside the building if underground).
