Hi,
I have done this recently on .net and my application works stable for 5 months now. You are right with Spy++. This helps identifying the window handles, that will change with each restart of the target app.
With my solution you will not have to use Spy++ manually, but the window will be identified by suitable attributes like window title or Window/control class names.
The only problem could be reading from the screen. The preferred solution is that the target app can be forced writing the required data to a file or copying to the clipboard by sending keystrokes. My price is based on the assumption this will be possible.
I have 10+ years of programming experience with C, C# VB, VBA.
Would be glad if you are interested. Please provide the exact verion of your operating system (Win7/8/XP and 32/64 bit) and .net installation (4,4.5, full, server, client profile).
Kind Regards, Mathias