Not quite as inexpensive and portable but I was happy to find we have a local health care provider using this test
Quidel Lateral Flow Rapid Test
on a drive-through basis providing results in 15 minutes. They charge $75 but they have to recoup their investment in the machine so I don't feel it's exorbitant.

This also uses the lateral flow technology.

One of the keys will be what tests will the island(s) want to see from arriving tourists? It would be nice if they would get together and agree . . . OK, I will stop dreaming now!