One additional thought, IF "they" want 50% now for something "they" are going to start in mid December, something doesnt jive here.

I suggest that you check out "they" with others who have dealt with them.

If the demand is so great, "they' might command this kind of deposit. For instance, Brookville 3 windows are probably in demand....Brookville asks for a $5000 deposit on their 3 window body..... and they are probably the cream of the crop.