Sometimes,
if you can supply your own parts and just pay the labour, you’re potentially limiting the amount you can be ripped.
My idea, order the urethane seat foam from wagonmeister, take it and the seat to your trimmer.
At least, they won’t be able to say we spent three hours shaping the foam and you owe us $1000.
Quick tip: buy a pair so you can do both seats, save on shipping from USA.