If its gun hunting we use office chairs in our box blinds. My father who is touching 70 likes to pick up a bigger and better office chair to bring to deer camp every year just to drive our buddies crazy. Last one was a high back leather chair with arm rests and a massage button (broken). I think it only cost him $30. I swear he does it just to get a kick out of his friends but I think he spends half the morning hunts sleeping so it works out for him.
For the rest of the blinds I have laboratory office chairs in them. They are the same as office chairs just made out of think plastic where the fabric usually goes. They are comfortable, rain runs right off and the rodents don't knaw into them. They really make hunts more comfortable when not seeing anything. I also get them if they are broken (missing wheel or don't adjust) for $5 and they are around $300 new. I'll just put a wood block under the missing wheel or adjust it and keep it at the same height.
I've also used the folding lawn chairs before. They are cheap and work well and usually cost less than $10 so if they break its not a big loss.