Based on your specifications I can't recommend anything in your price range.

Your measurements are more like a single bowl regular sink rather than a prep sink. Look for a sink to fit a 21" base cabinet that comes with a cutting board.

Sinks that come with cutting boards usually cost way more than the sum of their parts. It would probably be cheaper to buy the sink you want and have someone cut down a larger, stock cutting board to fit the sink.

You don't say what material you want the sink made from? A stainless sink can be under $200, quartz/composite under $300, and copper about $700 for that size.

http://ahturf.com/store/index.php?route=product/category&path=26950_10302

What if I was willing to spend a little more? Fred thanks for tips. Unfortunately we are not handy so I prefer to buy something already made to fit.

Cutting boards on sinks never make sense to me so you chop , peel and put the scraps where? This is from Ikea I have 2 of them back to back in my island they are great one i use for prep and one for washing what does not go in the DW they are very affordable and the sink part fits in a 24” cabinet with the drain board sitting on the top of the next cabinet my hubby does most of the prep and he just uses a cutting board on the drainboard side.