I frequent Taroda Racing recently and I have no comments in regards to the regulars there talking behind one anothers' back, as I do not know the regulars there well.
It is true that you will have to spend $50 on any purchases from the shop to be able to use their track for a year. By spending that $50, you automatically become a member of Taroda and will have a 5% discount on your purchases thereafter, may it be hop ups/spare parts/chassis.
As for the inflated prices, I fell that ultimately its the buyer's discretion as to where he/she would like to spend their money at. Though the price may be a deciding factor for most, some will be willing to spend slightly more for services such as trouble shooting/after-purchase care/service in general/shop convenience.
In relation for the need to spend a min. of $50 at the track, I suppose Taroda needs to pay a retal fee to the facilities management for ECP. It may be a stage built by the government, but still I reckon Taroda has to rent the space to be able to occupy it.