My suggestion isn't new. Indeed it has been a pretty standard part of retail business for decades.
*** Customer inducements and discounts ***
A fantastic way to inspire customers to part with cash is limited time specials. Offer "this weekend only" 3 for 2 on cash credit buys. At the same time, offer "all club sets 20% off".
Just about every player that has ever paid real money into the game will likely jump on such an offer. But the best bit for WGT is a whole lot that never have probably will. When combined with a pro shop offer the even better part for the WGT accountant is that a lot of the credits bought will get spent on the same day.
Such "schemes" are also a good reward for regular players. If an offer comes out of the blue "today only!" regulars will see it.
Every player here recognises that WGT is a business. I'm just thinking maybe in amongst the computer savvy and website savvy employee's, maybe WGT should consider getting a business marketer onto the payroll... ;)