Doco, If you go with the the ST-AV2pak-c, the price would be $5100+ programming. This would save you a couple of grand by not using the two-way. However, you would lose some cool stuff, like monitoring the temp of the tub, alarm and such on the touchscreen. But, is this really worth it? The one-way connection from the processor can trigger alarms or email to check the device. The alarm has a status button and will recall with voice and display from a one-way command from the Crestron system. If you choose the PRO2 processor, the monitoring or system limits can be shown on the front panel of the processor. All of the devices you mentioned have software "modules" and hardware interfaces ready to control the different systems. This is an important part that is lacking in the PC world of device control. Please show me a module for running the specifics of a Apex alarm or Jandy spa controller without the extensive logic and rs-232 commands for everything. You certainly can do PC control, but I fear the programming would be long and expensive, more so than a Crestron or AMX or Elan system. JMO. PC guys-show me otherwise. I honestly would like to see at CEDIA or similar a system running and controlling Vantage or Lutron, Jandy, APEX, GE, or DSC, as well as, Enerzone or RCS enviromental controls. Fully functional display and interconnection details too.
Doco, I see no reason for you not to use your relative. He can wire and set up all the subsystems for you and document and turn over the plans to the Creston Programmer. Make contracts with both companies in detail for their responsibilities. The more info on who is responsible for what will get your project completed faster. Sounds like you are the General-get those troops moving...