I imagine your best bet is to find someone locally to make one if you don't feel confident to do it yourself. Most any handyman/carpenter should be able to build one without too much work. It's basically just a piece of plywood or similar sheet goods with edge reinforcements, banding or other edge treatment, and some top surface (typically laminate, though there are lots of things one could do for that). None of that is particularly esoteric or tricky for someone experienced in such things.
Of course, if you want beautiful fit and finish and fine woodworking, it's entirely possible to pay someone a lot of money to do that...but not really necessary.
