I don't think this would bother a potential signing. I can't imagine a player saying "I was all set to join Villa until I saw the dugout, plastic seats, are you having a laugh, so I stormed out and back into my Bentley (which has comfy sports seats by the way)"
Keep it how it is, having comfy seats won't improve us, and who cares if it looks crap, I don't go to match to sit and watch the dugouts!