I am sourceing one at teh moment and I have not been able to find any second hand, New I am looking at about £1500 plus VAT, that includes delivery and erection
Can't help you with buying them as I am in the wrong country.....however make ultra-sure that you go for the correct size for what you want! If you buy one too small, I can tell you, you will very quickly grow out of it.
I personally wouldn't go for one smaller than 65ft diameter, which is what I have.
I went for the cheaper version that works perfectly!
Herris fencing (sort of security fencing) and then if you need too just board out the bottom few feet with plywood or similar.
A fraction of the price but just as good. Each fence panel with feet and brackets etc were £15. I got mine through the local free ads.
Good luck.