Hey Isaac,
as we’re all based in Europe and New Zealand, we never checked for US suppliers, sorry. It is hard to say without trying though, if these alternative magnets work. However, the crucial point is the grade of the magnet, as one can always adjust the .stl file for smaller ones. I just fear that smaller magnets might be to far away from the well to attract the beads efficiently. But that’s what one would need to try out, maybe with a higher grade. I would definitely not try weaker magnets than the ones we used (N45) though.
Cheers