I am in a very fortunate position and don't pay! My trainer's are very good and will help me at home and at shows and not charge me, but then in return i do help with there horses and if they are short of help at shows will go with them. So it is swings and roundabouts!
My RS charges to same whether it's on your own horse on one of their's as looked at taking up Baron last year. Looking at £40 during the week or £50 at weekends (and that's members' rates).
I tend to get taught by the cheif instructor who's an II (almost her I) and is bloody good.