I feel this is pretty accurate. How much does the off the shelf solution cost? How big is their team? You can take that into account when pondering on a dollar amount that would actually get what you want done. I mirror mywittyname's sentiment. If you get the right person in there they can probably do it solo. But its going to be a large number that you are not going to like. Otherwise you can hire more, less qualified people, at a lower rate and end up with the same or worse result and it will take 10 times longer. E.g. probably the team the solution you are using now has.