Hello,
I am very interested in this project, it sounds interesting and is a good challenge. I can build a demo for you that would include the following:
1) A few nodes to move around, supporting drag and drop
2) Node connections
3) Data loading/saving support
Please send me your design reference because the attached example you mention doesn't seem to be available here.
No payment is required to release until project completion, however I request full amount to be put into escrow if demo is accepted and the project is started.
Many Thanks,
Sergei