You use to be able to purchase unfinished table tops at places like Home Depot. You could cut it to size and stain and urethane it to match your woodwork. Another alternative is to purchase plywood cut it to size and cover it with matching formica.
I just threw away a complete Dinette out of a 2009 Keystone Hideout. They use chip board covered with formica and they tend to warp over time.