Yah I don't know why the availability of effective displays for car models is so hurting... there's basically nothing appropriate out there without custom building... bookshelves are so deep they're a big waste of space and you can't stack 1:43's on them in their display boxes... and, I mean besides rolling off, you can't leave them in the open because the dust comes and it's literally impossible to get out of all the little nooks and crannies or even around the windshield wipers and whatnot.
I use invisibly mounted glass/metal shelves from Ikea (varying lengths of this product:
http://www.ikea.com/ca/en/catalog/products/50201874/) that are fairly shallow and keep the models in their boxes... but that obviously doesn't work for the Signature AA models since they come in those shitty black paper boxes. Also, these suckers weigh a lot more than you'd think collectively, so I have had the horrifying experience of a shelf that I guess I didn't hit any studs with when mounting it originally collapse and dump like 50+ models onto the hardwood... all of them in boxes, but I still lost a few clear cases and broke the mirror off a F355... although most of the damage was to my shorts being woken up from 50+ models and a glass shelf shattering into the ground at 4am in the morning hahaha