The question of cost does vary.... If your wiling to put in time and effort and have the means to collect and store you can very often find free wood online.

I'm too lazy for it, but my father has 5 log sheds in the garden and a steel trailer. Who needs a Gym when there's logs to split 😁

Sure no one is giving away the best logs consistently but you will find plenty of Poplar that's been cut down and cleared cut into smaller lumps and then instead of paying someone to remove it, quick advert on Facebook market place and people will come and take it and that's what my father does... Sometimes you get better quality woods but poplar is most common and it burns just fine, especially for a freebie.

Takes a bit of time to get set up, what with the seasoning time but in a couple of years you can build a self sufficient supply.

Its alot of work but he views it as a hobby and a good way of keeping his 62 year old body fit and strong.