Would you be up for making a bin cage? If so this one is an ideal size and supposed to be easy to cut without cracking. It's hard to find bins big enough for a Syrian. Still doesn't work out cheap as they've also gone up in price and it's £60 for the box. Add the cost of mesh, tape and tools and it's not much of a cheaper option than the large Zoozone.
Go Shopping - Really Useful Boxes - 145 litre Really Useful Box
I think your best bet may be the standard sized Duna Multy and get an 8" or 9" wheel as well to fit it. But a wheel could be another £10 to £20. I'll look to see if I can find the large zoozone cheaper anywhere as then your current wheel would fit.
Cage Duna Multy | Welcome to Porton Garden Aquatic & Pets