With no idea in advance of what the actual pricing is, this seems to be the typical Vegas agency model that generally leaves people very disappointed (a search in the Vegas forum will show numerous posts by people who've had bad experiences with this model; usually the term is "ripoff agency"). It's an incentive for ladies to underdeliver services and overcharge fees.

Agencies and independents that have good reputations in Vegas generally don't do the "there's a fee to get your lady there and everything else is negotiated" routine; the fee that customers pay is a flat fee for time, there is no haggling once the lady shows up because the expectations have been clearly set in advance, the ladies are reviewed and are sensitive to their reputations, and the agency or independent stands behind their service.

I have to say I am very skeptical that I would ever use a service where I had no idea what I'd be paying until the provider showed up. I tend to think most experienced TER hobbyists who are accustomed to flat fees stated in advance would feel the same. The entire point of TER is to allow better matches between the expectations of hobbyists and providers, and that includes knowing what you're paying for before you make commitments.

I wish I could wish you good luck, but I'm afraid I can't; I think your business model is essentially deceitful and not in line with what reputable, highly reviewed agencies and independents in Vegas deliver. I suppose I will have to hope that you reconsider.