dave (ratking) does come highly recomended on here and can build almost anything at a reasonable price but if you are skillied enough you could always build one yourself easy enough, we have just built 2 stacks. each with 1ft at the bottom divided in the middle which we keep 2 storage boxes holding substrate and other reptile related stuff. above this we have our first viv 3ft wide by 2ft deep and 2ft high and then the same sizr viv above this. everything in all cost us just over £100.
you do however have to have the time to put into it and immaculate measuring skills.