What states require non-refundable due diligence fees?

[Laura Siclari]

Real estate investor looking to expand into new markets in other states. I became aware that North and South Carolina have this practice of requiring due diligence fees that are included with the offer and are paid to the seller and are non-refundable if the deal doesn't close (subject to a few exceptions). Do any other states require due diligence fees? It's not a practice I've dealt with before.