Flat rate plus tiered pricing ask

Summary

Any insight on creating pricing structure of flat rate price (regardless of quantity) and tiered rate (using quantities) for a single item

Content

Good evening all, I have a request to see if we can price an item using a flat rate (e.g. $2k one time install fee regardless of quantity) along with a tiered rate (e.g. $15 each for an item quantity 1 - 300, $14 each for an item quantity 301 - 600, etc.).  So that if a customer ordered 350 items, price would be $2k + $4900 (qty 350 x tiered pricing at $14) = $6900.00. I know this pricing can be accomplished having 2 separate items using one pricing rate each. Just looking to see if anyway to do