They're esoteric enough that I'd be surprised to see a reasonably-priced one.
I've made a simple desk in the past with an ikea top like this one http://www.ikea.com/us/en/catalog/products/S29870932/ and four lengths of 100mmx100mm planed softwood for the legs, and four big (10mmx200mm) countersunk screws down through the top into the legs.
It was surprisingly sturdy, and takes a few minutes to assemble once you've got the parts.
I've made a simple desk in the past with an ikea top like this one http://www.ikea.com/us/en/catalog/products/S29870932/ and four lengths of 100mmx100mm planed softwood for the legs, and four big (10mmx200mm) countersunk screws down through the top into the legs. It was surprisingly sturdy, and takes a few minutes to assemble once you've got the parts.