I don't know how much they sell for now, but I was lucky to get one for $20 when they were normally going for $40 on eBay.
I forgot the exact result, but I once calculated the value of a 100 trillion Zimbabwe dollar bill when it was printed, and it came to something like 0.06 USD (6 cents).
There are also fakes, most of which admit in the description that they are fakes, and include extremely large numbers like 10^33.
The highest number that you can get cheaply and that is not fake seems to be the 50 billion. They sell for about five dollars, which given the economics of ebay is probably as low as you can expect.
At one point I had a hundred stack of them somewhere.
I'll try and get a copy. This was 8 years ago, but the lab will probably still have a copy. I felt like Dr Evil... one hundred trillion! All I could think of was this skit:
It was a single (real) $100 trillion bill from Zimbabwe that I carried in my wallet for fun. I assume they thought for some reason it was US dollars?
https://www.banknoteworld.com/zimbabwe-currency/100-trillion...