I think you might be talking about the CV boot that goes over the CV joint? On the steering rack underneath the car? The boot it's self shouldn't be too much money to be replaced. Worse case scenario is that sand, dirt, or water might have gotten to the cv joint and damaged it. If that is the case later down the road it isn't too much money to get a steering rack. Maybee $300-$500.
As for your window. It sounds like it's your motor if it won't go down at all. It's not that hard to put a new one in and won't cost that much. Maybee $100 or so for a new motor. I've also dealt with cases where the window tracks have been binded up on something. But you'll usually notice in that case that they will move up or down a little bit of the ways and maybee not align correctly at the top. Something like that might happen if someone tried to break into your car or something. But how you describe it, just sounds like a window motor.
If the price is right go for it. The things you mentioned don't seem too bad.