I have always been thinking about designing something of this nature but have never had the funds or time to do it. From the price of this set, I still don't have the funds to do it. But I think I can somewhat improve on the design a bit. I am thinking about writing a homebrew app for the Nintendo DS.
I just found a automatic door actuator that is compatible with the X-10 system. The X-10 system can be easily converted to the SmartLink frequency.
On an average house (2 Story, 3 bedroom) I estimate the cost to be around $3,000 to automate everything. When I purchase/build my own home, I am definitely putting this system in. And hopefully by that time, the price for this will have tremendously decreased.