Pay for small sided college tournament

Can delete if this is not allowed but not sure where else to ask

Was recently asked by a local college (d3) coach to help ref their spring tournament. 7v7, quick 20 minute games and he asked for a rate

What would be a good price point per ref? Should I do per game or ask for a lump payment on the day?

Would be 27 total games between 2/3 refs

Previously they’ve had had 1 ref per field and 2 do the final

Based in Eastern NY if that helps at all

TIA!