Are you interested in just some panel mats?
You can find some 4x8x1" to 2" panel mats for around $100
AK Athletics Factory Direct Folding Panel Mats (http://www.akathletics.com/servlet/the-Folding-Panel-Mats/Categories)
Otherwise you could check for some used ones.
Tiffin Athletic Mats - Clearance (http://www.tiffinmats.com/clearance.htm)
If you want a thicker landing type mat, $500 is going to be a relatively good price.
Sometimes you may get lucky if you can find a school that has yearly "garage sales" and they are selling some of their old mats. You can get some really good prices there. If you are in a big enough city you may be able to check around yet this year and find some.
There are some schools that will not sell equipment for liability reasons so just know that you may find some of those too.