I gotta dig up a pic after I sanded 24 feet of Blackfin down to GC. Or on my first boat when I was "bottom man" as my buddy knew electrics very well and got burned just looking at the sun. So I became every year, "little smurf", or that's what I looked like.
No way I'd gripe about $1100 for a 31' hull. I know what you're saying about price matching but in this case if the work was done according to your instructions I'd suck it up and run. Next time get an itemized estimate, including costs for Tyvek suits, brushes, hazardous disposal, etc.
Hull prep and painting is a thankless job. My $.02.