I have Covid 19 antibody/ antigen test kits. (40 tests).These use fingertip blood and check for both current infection and post infection immunity. These were sold to hospitals and medical centers. They are recently expired but foil sealed and are still accurate and usable. At 1.05 per test, the price point cannot be beat.
The kit includes fingerstick devices, alcohol wipes, and clear instructions for use and interpretation of results.