That is interesting they no longer make PCI compatible hardware - the key thing is make sure whatever you get is on the HCL that will ease any installation issues - look at HP they have a number of good lowend server hardware - that you configure into your price range - when sizing make sure you account not only for the VMs but also the ESXi requirements -
I used to be an instructor and would always tell my classes if you have a reasonable amount of technical experience you can set a VMware environment - - VMware has great documentation http://www.vmware.com/support/pubs/vsphere-esxi-vcenter-server-pubs.html