I'm in Eastern Ontario and I've gotten quotes from about 15 barns in my area and all were the same price range. Seems that's what my area is!
If you want to ride a show horse, then you must be taking two lessons a week, which is $250. Otherwise, it's a schoolie for $140 for once a week lessons. Some of the schoolies are more advanced for sure, but are not comparable to the show horses. This is actually the average price range for my area. Other barns I've seen once a week has been: $185, $150, $160, $190. These are all 60 minute group lessons.