Home Depot has some inexpensive sinks in a variety of sizes, designed to fit atop a cabinet. The one I got was supposed to be simulated marble. I think it cost about $100 for sink, drain assembly, and faucet. It was easy to install and looked good, but it did pick up mineral stains. It got so the stains weren't coming off, so I replaced the whole thing after about 5 years, for less than $100.
Not fancy, but not a bad deal.
-Joe-