Back to this interesting .tv thread with another few noob

questions. Let's say I am interested in purchasing a very nice .tv name from a seller. I know the name is a premium but how can I make sure before the purchase :
-that the reg fee given by the seller is the right figure ?
-that VeriSign, taking the opportunity of the effective change of ownership, will not in the meantime increase the reg fee of the name ?
Last question : how/why a sale can change a high premium reg fee to a low $100 or a $50 standard fee? Is it a case per case agreement to be met with VeriSign ?
Thanks for your reactions !