See if you can find a place that sells used office furniture. You can get a decent one pretty cheap.
Check with the schools around and see if they have any old ones.
First try thrift stores. Then estate sales. Then antique auctions.
Garage sales, second hand stores, Craigslist...
I am doing online school and need a good desk to do work on, i ordered a hutch on accident.. so im trying to find a desk for a good price..