It is difficult when it’s hard to find good wheels and money is tight but I have to agree it wouldn’t be safe really as you wouldn’t be around to supervise at night. My concern would also be a toe or foot getting trapped, the ball toppling over (depending how stable it is on the stand) etc. Most balls are also too small for Syrians as well so he wouldn’t be able to run with a straight back. That is also the issue in a wheel that is too small. If they run with a curved spine they can develop back pain and need vet treatment.
An upright wheel is what they need - minimum 8” diameter (for an average sized Syrian) but ideally 10 to 11” diameter. A ball needs to be 10 to 12” diameter. Most balls are only 6 or 7”.
Can you get things on Amazon? If not this link might help. Zooplus do very reasonably priced, safe hamster wheels - the plastic trixie 28cm wheel is cheap and a good wheel. I am not sure if Zooplus delivers to turkey or not - they deliver to most of Europe - but this site seems to offer a service to deliver Zooplus purchases. I’ll link the wheel as well. Actually zooplus don’t have the plastic wheel right now (probably covid supply and demand). So I’ve linked it on Amazon below. UK Amazon might ship to turkey if you try going through checkout. Zooplus do have the wood trixie wheel which is a good wheel and about the same price. But most people paint if with pet safe waterproofing paint and that might be difficult for you to get hold of.
https://www.colisexpat.com/pages/en/...rquie/zooplus/
https://www.amazon.co.uk/Trixie-6101...e+wheel&sr=8-1
https://www.zooplus.co.uk/shop/small..._wheels/609617