$4999 is missing and would be a little better. But the $6000 isn’t bad for what it is.
I think that's a fair price. That should be about the refurbished price when those become available next year, or maybe sooner if a retailer offers $1000 off like Micro Center did with the iMac Pro just a month after release.
The iMac Pro also has a screen, so why not?
I have voted $4500, as that would be nice, but we are basically all armchair Product Managers on this, and I bet there is a lot to take into account that we just don’t know about.
How long does it take for it to show up in the refurbished store?
Custom built is always cheaper than buying a complete box. Go spec the same thing with HP and Dell and you’ll see the same price jump. Apple isn’t a charity. And no PC vendor competes with custom built prices. I don’t know why suddenly everyone is pulling out custom built comparisons like any vendor is price competitive with that. Complete systems always cost a lot more.
Custom built is always cheaper than buying a complete box. Go spec the same thing with HP and Dell and you’ll see the same price jump.
No, you don't. HM Z4 with 3.7 Xeon W (last gen, but the 3223 is only just out and is much the same price) is around $3500: https://store.hp.com/UKStore/Merch/Product.aspx?id=4RX30EA&opt=ABU&sel=WKS (remember to knock off 20% UK VAT before converting to dollars). If it costs you $2500 to add 10Gb Ethernet and a SSD to that, you're holding it wrong - and if you have a use case for 8 PCIe slots compared to the 4 or so in the HP, do tell.
I've build my own PCs in the past and - even if you don't cost in your own time - you don't save money on like-for-like unless you can get components at trade prices or hunt down surplus/bargain deals. You do it to get exactly what you want (which may be better value c.f. a pre-built with parts that you don't want/need).