Honestly, the cost is mostly up to you....check with other sailors in your area as to who has made cushions for their boats...
we went to a home upholstery shop and had them made for our O'Day 272 twice....once just the settee cushions and then later for the berths....each time (realizing it was not the entire boat)...we spent maybe & 450.00 or so.....we had the big quarter berth cushion done separately in vinyl because we are always using the quarter berth to tore items like the cockpit cushions, etc....fans, duffels...etc....and we thought the vinyl would work better and it has....but I'm not really desiring to have the settee
cushions, etc. in vinyl....Our boat came new from O'Day with a blue flame stitch material that reminded me of a Texaco
service station restroom so we replaced that right away...(maybe two weeks) after commissioning of the boat....it was fun picking out the material and colors as it makes a huge difference in the boat's interior livability....Have fun ! Pat