If you really applied yourself you could find a good used (less than 500 hours) 52 and a 36 for that money. Heck, you could find those 2 mowers for probably $4500.
I'd try and find a 48-52 Wright stander and 36 Exmark walk behind.
Quick search...took 2 seconds
http://dayton.craigslist.org/bfs/3564825422.html
I'd offer the guy $3500