Cheap reliable place to have replace a nikon D40 mirror as quickly as possible?

Cheap reliable place to have replace a nikon D40 mirror as quickly as possible?

Nope

Unless you have broken the mirror put up with any scratches you may have put on it by trying to "clean" it.

Replacing a SLR mirror is a very precision task and must be done by a skilled technician

It is not going to be cheap or quick. The best way is to have Nikon do the work.