a solution for some, particularly if you don't have good sources or storage capabilities at home, is to find a couple spots where to get some scrap lumber, gather what you can, and bring it along, then buy whatever it takes to make up what you need for a trip, a simple stop to grab a couple free pallets, or a couple box fulls of scrap lumber from a building site or cabinet shop, could firstly net you some good dry wood to mix with the usually not so great park wood, or at least not predictably good, and second to reduce your cost by buying allot less.
I have a 8x10 shed and half of a 10X12 full to the ceiling of scrap I acquired from a trim and flooring mill, I figure if I don't acquire any more (as that source is now redundant) I presently have enough for about 15 years of average camping trips. why so much? well with that as lets call it a cushion of time, as I stumble across more here and there in my daily work I can add little bits to it all the time and keep a significant supply for up to if not over 20 years slowly depleting unless I come across another score like that trim and flooring mill, its all indoors and bone dry, I have a couple totes that I can fill and throw into the back of the truck that holds enough for a 4 day weekend easily up to 8 days if I pile it tightly in without the totes, right in front of the hitch.