Although I haven’t tried it myself, I hear good reports about using a thick, brush-on coating called melamine paint. Although this stuff is very tough, you’ll still have to be careful not to scratch the surface after it’s dry.
Another approach is the in-home installation of a new layer of Formica or Arborite over the old stuff by a cabinetmaker. This would save money compared with a new top and make good use of what you have. The same contact cement that holds the current plastic laminate in place can bond a new layer to the old.