It is a well used Indian Leather GP, made by Saddlecraft now and sell new, fully mounted for $299.00. The price you paid for a second hand one of these is about what they normal get.. as long as the tree is sound (you should get this looked at before putting it on a horse, also check all the stitching, as it looks like it is coming apart in a few places) - to measure the seat size, take a measuring tape and measure from the button at the front of the saddle to the middle of the cantle (the high part of the back of the seat). It also looks like it has the original leathers and Nickel plated Stirrups. Hope this helps..
Horses only respect people who are consistent and fair and they only trust people they respect.