300 feet is at or beyond the edge of copper CAT cables, I'd run multimode fiber of the appropriate type (run a few to be safe?) - fiber doesn't care about power interference.

NOTE: See comments - I ran multimode because that's what the connectors in the off-lease hardware I had came with. Seems single mode is better in general.

https://www.lanshack.com or similar should have something in the $400 range.

You could be super cool and run conduit, but that itself has a cost (spooled conduit is what I'd do, but costly)