Childrens potties from the pound shop. They are a good shape to cradle the pole without them rolling off and just go to the timber merchants for round poles.
I would either make some out of wood if you are handy and have the time and wood or buy some potties. Potties make excellent pole holders as they can be knocked and just roll in the potty so actually better than wood.
I have fence rails and posts.
The rails have a flat edge so are better for poles on the floor as they don't roll, then the posts I had the pointy end sawn off and use for raised pole exercises. I got 3 poles and 2 rails (which I then sawed in half to give 4 flat edge poles) for about £60. Far far cheaper than buying proper jump poles, though they aren't as long as normal jump poles to be fair.
Few cans of paint and some afternoons well spent and sorted!
My blocks are from poly jump, they had a special offer on them at Easter.
I'm fairly certain a previous yard just used wooden poles from a timber merchant as LL suggested and painted them. They're just a bit heavier (with the occasional odd length!) than their plastic counterparts