As a veteran of multiple E46 window failures, I can give some advice. Just remember that you are getting it for free and that is more or less what it may be worth.
It is not too hard to do it yourself. Get the door card off, undo a few nuts and put in the new one. The screws holding the door card in place are of the Torx variety, so you will need a special screwdriver. Getting the door handle cable back on is a bit of a hassle. Only if a bolt is rusted and stuck does it becomes very tricky. Don't ask how me I know that. I am sure that there are videos to show you how on the internets.
Note that there is a piece of foam rubber protecting the door card. It is glued to the door using a tar-like substance. Wear old clothes, it is nasty stuff that sticks to everything. Don't ask. Sigh. It is easy enough to peel part of the cover off but be careful about it and do not tear it.
If you don't fancy having a go or do not have the new parts yet, there is still a plan to get you around if it rains. Pull off the door card and push up the window by hand. If it won't move, undo the bolt holding the window to the mechanism. Use duct tape to hold it in place, but that leaves a nasty glue mark that has to be cleaned. Don't ask. Anyway, it also alerts thieves that it would be easy to get into the car. A better plan is to find a piece of wood of the right size to hold the window up.
You can then leave the door card off and drive to the shop tomorrow or whenever. Opening the door is a bit weird but one learns to manage. Don't ask. Or you can make sure that the wood is a nice fit, in which case you can refit the door card and drive around with a non-operational window. This tided me over when I was between jobs once. Just use solid wood (pine is OK) that will not disintegrate when wet if you do this. Don't ask. :=):
