An aftermarket condensor should be in the range of $150 to 250. Replacing the condensor itself is not a big job; a few small fasteners and a couple of fittings.

A new receiver/dryer is a good idea to take up the moisture that's been introduced by the system being open (due to the leak). Add refrigerant and a couple of hours labour, and you're looking at $500 to 600 in a good independent shop, more at a dealer. If you get it done for less, you've got a good deal. (AC repairs are always pricey, and almost always inevitable.)

If you're a DIY'er, consider replacing the parts yourself and bringing it in for the refrigerant. It's basic plumbing, really. Or you might want to research aftermarket altenative refrigerants you can install yourself.