That is a tricky one, a lot of people a attempting that right now, I also see a lot of people abandoning their projects unfortunately too. I think that $1000 dollar mark might be hard to hit with out you actively scouring e-bay (it can be a bit of footwork, if you don’t know what your looking at proc part numbers, chipsets, etc, etc) and getting a combo its just do you want to buy cpu’s and seek out a motherboard or the other way around? I think get your self the board first and go from there. I like the 2 of SuperMicro boards I have had a slim chance to use, I’ll see if I can dig up part numbers. I see way more proc’s at reasonable prices than boards. What I/O do you need? The other issue is cases (standard pc) that fit most the boards you see, E-ATX and larger (or propriety) tend to be more expensive and used ones don’t come up as often do to long service life, IMO if your going to go through with it you might as well have a sizable amount of RAM and I figure, if it was me I would go ECC if I was going to utilize server/workstation grade components, some combos will require it. That also adding to cost. Do you have any components? It can totally be done, I have seen many people put these together for pennies on the dollar, between eBay, surplus, and a little dumpster diving. Check out PCpartpicker.com, Level1techs.com forums (for additional help), Intel ark, and builds.gg. But it really sounds like you need to figure out really what you want, and what your expecting… What OS? With out doing a little more research its hard to expect much help, these guys are here to help but not be salespeople or complete tech support… I am hoping to do a dual Xeon build myself, in the next year… You might also consider a older Apple G5 setup, and upgrade it to the gills on the cheap and end up with a lot of processing power on the cheap. There are Tek Syndicate videos on both these type builds. just take a look. If I get rolling on my build I will keep you updated, if I run across any great deals, I will post them.
Heres one https://youtu.be/IuW3HuzYWsw !!!
all in the same vein, should help you get started