Bench or buckets?
There was a member here that had a line on some grey leather bucket seat covers. Door panel inserts, too. Aftermarket repro's, but very nice! They were a C/L find, in Texas. (?) They were going for $300.00! Original cost was something like $1300.00!
Those could be dyed, but IMO they're too nice to do that to. Or, if you could find out the manufacturer, they may have blue covers. But then, $1300.00!!!
Or you could get the seat(s) redone by a good upholstery shop. An auto upholstery shop. NOT a furniture upholstery shop. (Those guys don't 'get it', when it comes to auto stuff!) But...for a set of buckets, you're looking at $500.00'+', just for the leather, depending on the quality. It has to be leather for vehicles. Mold & mildew resistance treated, & U.V. protected, too. If it doesn't have those treatments, it won't last, & you're throwing money out the window.
Vinyl = $20-$30.00/yard, approx. (36" X 54")
Leather = $10.00 (+,+,+,!!!) sq.ft. 18 sq.ft. = 1 linear yard, or $180.00 a yard!
But leather will last 3-5X longer. It breathes cause it's a fiber, not a textile, & is much nicer to sit on for extended lengths of time.
Probably a bit more info than what you needed. I got on a roll! Lol!
Hope this helped.