For spec based hardware requirements to run UC applications refer to this:
http://www.cisco.com/c/dam/en/us/td/docs/voice_ip_comm/uc_system/virtualization/collaboration-virtualization-hardware.html#servercompatibility
If this is for lab and you don't expect Cisco TAC support on it, you can install the apps on pretty much any ESXi host. I run my lab on Dell R710 with 12 CPUs cores, 64 GB RAM, 4 TB disk and it runs very smooth for lab purposes. You can pick these types of servers on eBay for $400-$600.
