You could also buy 2 cheap xeon processors that are refurbished like:
http://www.ebay.com/itm/SR0KX-INTEL-...203?rmvSB=true
http://www.ebay.com/itm/Intel-Xeon-E...sAAOSwqRdXMgFy
Than just pick up a dual socket motherboard (cheapest one I saw new was 275 Euro's) and throw in some ddr3 ram (also cheap since lot of people are switching to ddr4) and add a second hand gpu like 970 (200 Euro now). With this you should easily be able to multibox 25 characters on 1 system.
The only problem is that xeon's do not go well with most other games because they do not use all the cores (it depends on the game since you can run some on an i3 with a gtx980).