"AFAIK any control system that can do IP and serial communications is going to be sold by a dealer. A used 3-series processor and an HR-150 would be a more budget friendly solution. "
I agree with Ryan!? (And also with Thorsten - C4 not that different $$$)
Though used Crestron stuff on eBay is more expensive then it used to be, It would likely be simpler and fairly similar cost, and you'd have all the control and it is familiar with the support you are used to...
I learned the hard way years ago, that dealing with and supporting a one-off solution is not a great deal...
