5 years ago when i was solely based in Toronto and only wanted to work on occasion, my donations were $450/hr(daytime) & $600/hr(evenings & outcalls). I visited part time and had no issue getting bookings, and if I had wished to entertain full time I am sure that it would not have been an issue.
Companions will charge a donation that they feel they are worth and one that the market(bad term) will support. What may be out of reach for one is not so the case for another.
Some may not understand why someone would drop $500+ an hour on company, but that is ones personal choice, one that others have no right to criticize judge or bitch about.
Good company comes in all shapes, sizes and donations, when you find what works for you, make the most of it.