We sold Scott Arfield to Huddersfield after the 2009 SC final. Since then I think we've sold the following (in no particular order):
Arfield, Stewart, Flynn, Murdoch, Wallace, Higginbotham, Taylor, Fulton, McGrandles, Kingsley, Blair, Biabi & Vaulks. Don't think I've missed anyone out? Most of these came through the academy.
I seem to remember that Arfield's fee rivaled Yogi's to Celtic which was £375000 but would have been significantly more with the add-on's that were paid. I believe that the smallest fee on the above list was Murdoch's which I think was a £40000 development fee however the others would have been significantly more and I reckon we're looking at circa £3m (conservatively) without add-on's which would have amounted to a hefty figure too.
So, without those fees we would probably have been out of business as we're currently running at a loss hence the cost cutting exercise of scrapping the academy which, rather ironically, is exactly what's been keeping us going over the past number of years!