While some of you guys seem to be tripping over A4000's, the rest of us have never seen a working one even once in real life... and I've been using Amiga's since 1991, lol. Like hen's teeth! *cough cough* *hoarders* *cough cough* 
I always wanted an A4000, back when they were new and $5000. One came up through eBay "with issues" I jumped at it. In the end the "issues" were the fact that 2 of the memory modules had worked loose. It is a badged 030 but had a 040 in it. The base chassis was bent so badly under the power supply edge the floor almost touched the power supply. I spent time and effort bringing it back to a good usable state. I paid $350 for it, back in 2009 (I think).
That was around the going rate then.
I have one Amiga 4000. And it's mine, my birthday present, my precious!
I consider myself a protector/custodian. Not a hoarder.