In my opinion, your best option would be to get a furnace or boiler into the basement somehow. Even if it means relocating your laundry appliances upstairs somewhere to make room for it. That way you can run duct work or plumbing for your new appliance easy AND any lost heat from the appliance will keep your basement warm and also help warm the floors on the first floor. I know what its like to use a pellet insert, propain and electric. I did the same before the coal furnace.
You can continue to use the pellet stove during cool months before and after winter.
If you have a limited budget, a coal forced air furnace and duct work can be done relatively easy and cheap. If you have the budget for a boiler, it would probably be a little more comfortable. You can find nice units on Craig's list.. Just watch and be patient for the right opportunity.
You got all summer to make it happen.
Right now is the perfect time to figure it out..