You can still find barebones on Ebay, but they are often just stripped laptops and you have to hope they work when you get them.
I did a little research on this last week. Only reliable places to get chassis, coolers, and screens from seems to be resellers for Clevo products like Sager. And then you have to ask specifically, likely paying a premium. Direct from OEM is a little tricky as they don't tend to take orders of one. Paying more than full price for a 'sample' of one might be the only option there.
Certainly no cost savings to be had unless you have access to someone that is ordering trays of mobile CPUs/GPUs.