Best experience for best value is what all people want in anything. As far as the hobby is concerned, that could mean many things, but from the way I am reading it is the OP is looking for the best all around service (once again, opinions vary upon who you ask) at the lowest donation price. To be honest, that is a good question and for the guys who have found a provider or two that is like that, I doubt they would reveal or at least be hesitant in doing so to let others know who they are, especially on an open board like this because the provider being flooded with calls/requests and coincidentally, she will raise those donation prices due to the demand, hence the GPS factor that has been talked about on this thread.
As has been said, the ideal opportunity to get that best value for the least donation price is by getting a provider who is just starting out, (but it is the proverbial shot in the dark) be it on BP, Eccie, P411 or whatever, as she wants to actually please sometimes going above and beyond to get that repeat business building up her clientele and has not become jaded on johns are nothing but ATM machines as of yet. IMO, it is rare, but not impossible that you will find a provider when she has been in the business for a while, who really and truly enjoys what she does and makes sure you do as well and take care of you from the first moment in a session to when you part ways afterwards ......those are the ladies who are the very best value.