I did some various window shopping online, and will highlight three sites that I think take different takes on the same problem:
First, IKEA. IKEA provided a traditional drain protector, like the one I described in the roommate focus group, but it sold it with the whole piece of sink drain as well. I think it sold it this way, still for a comparable price to just a drain protector, since IKEA markets whole sink/basin and related products for self-installation, including everything and the kitchen sink (ha ha).
They also included their clear diagrams of this product, as seen above.