I quite like the proposed equation. ~0,5 cost @ 25 range is a really sweet point to me,
As a random thought, what effect would making different tiers of boost / resource have different transfer costs be? Atm the t1 boosts, do not see much trading at all, even for new players. If they were to have lower transfer fees, or a wider transfer range, than t3 boosts, it may make them more palatable?
On the whole I really like the idea of regional markets, provided that each region has equal maturity (a regional market of only new players would sort of suck).