£250 is probably okay if it's genuine Yamaha decals and not Ebay copies. I know when I looked at doing my Tohatsu, then the genuine decals were over £90 alone, and that's going back a few years. I ended up getting a replacement cowl as one came up at a decent price.
If there's scratches on the cowl, then that needs to be sanded back, build-up primer, sand again, undercoat, base colour then a few coats of clear lacquer. You can see why it gets expensive.
Also - very difficult to do this with rattle cans compared to spray gun and the right facilities.
More details here on paint codes, just double-check with a main dealer to confirm. https://blog.simyamaha.com/yamaha-paint-codes/
There's a 75hp cowl here (missing the end locking bracket)