After reading all the above, it sounds like my cage would be perfect! About the same size as the Alaska, but lower and has 7mm bar spacing and a big front door. It might be a stretch for you pricewise though. It is intended as a cage for mice, like the Kios (hence the small bar spacing) and it comes with a metal grid shelf that needs taking out, as not good for hammies feet. It also comes with a sputnik, food bowl, water bottle, and a 6" wheel and some savic tubes for use as toys inside the cage. The wheel might be a bit small or might be ok. it will easily fit an 8" wheel in and when the base is filled with substrate, there are no height issues for falls but still room for ledges and a hammock or shelf. I bought it for a Syrian because I wanted a mouseproof cage as we get house mice occasionally and wanted to be certain one couldn't get in! I really love the cage because it is so well made and has the lovely big front opening door and also all the roof space is useable for attaching things to, with the door being at the front. I personally feel it is not quite big enough for a Syrian but it would be a great size for a Chinese. Smaller than 100 cm cage but still a good size. It is very similar to the Alaska, but lower and smaller bar spacing, although Cypher had an Alaska for her Chinese and says the bar spacing is fine. I guess it may depend on the size of your Chinese hamster?
Anyway although it is over your £50 budget, it does come with everything you need except a little house maybe and the substrate for the base of the cage. I didn't put another shelf in as with the base full of substrate it's not that necessary, or you could have a house roof as a shelf or some smaller ones attached to the side (I have a small lava ledge.
Have also attached a photo of Charlie's current set up in this cage (bearing in mind he is a large syrian so has a huge wheel and a rat sized sputnik in there! the smaller sputnik at the back is the one that came with the cage).
Anyway, here is the Savic Mickey 2XL. It is £78.50 but delivery is free. It isn't easy to find and I haven't found it cheaper anywhere else - maybe £7 cheaper at one store but then postage was extra which made it more expensive. It's a good investment cage too as suitable for any kind of Hamster, big or small. There are other Savic Mickey cages which are way smaller, so it needs to have the 2XL bit at the end. there are some slightly larger gaps down the top edges but they're fine too - only 8mm. One bar on my door where it curves is bigger than 7mm but only just. I put cable ties down the edges to tighten the gap up, but you wouldn't need to do that for a Chinese hamster - the gap is only about 8mm - I was just doing it because mice can get through anything bigger than 7mm. I found it really hurt paying so much for a cage, but I really think it is worth every penny as it is so sturdy and well made, I love the big front door, the top fits on and lifts off really easily, it has a nice deep strong base, and it is totally futureproof for any kind of hamster. As Charlie is such a big syrian I would rather have a 100cm cage, as he doesn't have enough floor space with his big stuff in, but he is happy in this one.
Savic Mickey 2xl Navy Blue Mice And Dwarf Hamster Cage 80 X 50 X 38 Cm: Amazon.co.uk: Pet Supplies
Here it is in various different set ups over time! The most recent is the last one, plus I did a cage tour video of it so have added the link for that too (again bear in mind it is full of big stuff for a large Syrian, so looks a bit cluttered).
Took the hanging ladder out as it seemed to be a hazard. I originally bought a savic shelf to go in it but it was a real pain and I was glad when it broke lol!
Link to cage tour video
https://www.youtube.com/watch?v=ZY4DPynt--Q