A retort:
1)I've used acrylic myself and found it pretty easy to get good bubble free joins... The company I've sourced is an aerospace industry, I'm sure they know what they're doing, people in the aerospace industry are very exacting in their demands and for very good reason.
2)The acrylic is computer cut, no issues there.
3)I spoke to them about this before I found out it was cheaper to let them build the cubes, they're not allowed to use any glues that aren't tested by the government to ensure strength and chemical properties under load and their stress thresholds, this information then has to be published so that strength and stress ratios are available to the end user and to make sure the correct spec glue is used.
The reason for not getting an optiwhite in this size is simple, one is less than £30 the other is over £160.
I simply can't see where the £245 asking price comes from, not when I was quoted £60 for a 12" cube in 12mm acrylic, made using computer aided design and manufacture.