A lot of cheaper ones do not have a very good weight distribution system. If you get one that doesn't have the correct distribution you run the risk of hurting their backs.
If you end up getting one anyway, you need a ticker more substantial saddle pad to make up for the lack of the weight distribution.
Alot of the name brand companies and dealers allow a test period. Maybe look into that... When I got mine I had a trial with freeform it was only like 160ish dollars. If you don't like it then return it and get your monies back, less shipping.
Well worth it IMO. :)