You could try a Catering Supplies company [dishes, pans etc] I have bought small oblong stainless dishes to use as sinks, you just need to punch a hole for the waste and make a cover or buy a stainless cover to match, they are used as food display dishes or in a "Bain Marie"
I've got this one, bought new, un-used, you can cut it down or not, make your own top, yours for price of postage. It's a bad picture and rather dark, and the sink is dirty where it has been lying around in my garage but it is stainless and actually wipes clean.