Ah well spotted Amity! It does say formaldehyde free. It's hard to tell from a picture but it does still look like bare chipboard although mentions "laminate plate", so maybe it is laminated on the inside? Maybe you could ring them and ask. I think otherwise I'd still be a bit iffy about chipboard and the chemicals.
Junglepets make custom built tanks. They make specific ones for hamsters which come with a wood and mesh lid, but none of those are particularly large.
They will make one any size you want but something the size of that vivarium would probably cost about £150.
The biggest hamster one is 4 foot but it's only 15" deep which is worse than the detolf
I think I was quoted about £125 for 100cm x 50cm x 50cm tall a year or so ago.
Small Animal housing
Custom aquaria also make custom tanks like Hamsterita's. They would again make any size you want, with a platform if required, and a deep base with front opening doors above and a mesh lid. But £150 to £200 ish probably.
You could just get a tall kitchen larger unit carcass and tip it on its back and make a mesh lid
It is mdf but enclosed in melamine. It would come flatpack so you could maybe replace one panel with perspex.
IT Kitchens White Standard Larder End Panel A | Departments | DIY at B&Q
There is also the Living World Green Eco Habitat - the large one has excellent floorspace - it's just under 4 foot wide but is also 78cm deep so a huge floor area. Also £150 though.
Living World Green Eco Habitat | Free P&P on orders £29+ at zooplus!