I agree with L2R but I would avoid the Ralide tree unless it is American made - like anything else there are different qualities to that tree. Also, fiberglass is to be avoided but not fiberglassed covered
hardwood - a very popular and sturdy tree made quite often by Steele tree company and used in a very wide range of good American made saddles.
If you are below the $500 mark, then look for some used saddles made by TexTan, Circle Y, Simco, or Billy Cook as an example. You can usually find them in the $350 range.
As everyone suggested avoid those "Western saddle packages" found on ebay
for $350 and below. They are imports and the quality of the leather and especially the tree is poor.