I found a great source of build bench tops.

The companies that make Laminated (Melamine) bench tops for Kitchens etc often have "rejects" that have been made to the wrong size or have a slgiht flaw such as a small crack in them. It is usually cheaper for them to make a new one than try to salvage the old one. They will sell the rejects for next to nothing otherwise it costs them to store or dispose of them. My main bench is around 12 feet long long and had a small crack in the melamine at one corner. The base material is 2" thick and there is less than 1/16" between the highest and lowes points on it (I looked at it with a laser unit out of curiosity).