It might be interesting for you to know that a "Professional Shop" that we all know about does not even give a warranty for the work that they do. At first you might think that it is a better than average conversion, but it is no better than your next door mechanic using parts out of a junk yard and converting your car to a 5 speed. The guarantee is good until you get it off the parking lot.
I think the value is in whether someone wants a 5 speed or not. Some may not want a 5 speed, so it would not be a selling point.