Yes, I have seen this. Its popular as rvosd, and I love its display. Its a good price considering a complete system. Only thing I like with eagle tree is with or without OSD each system is standalone and logs the data. Even in normal flights I could get the flight data and analyze and optimize for the next flight. A full autopilot in my opinion is needed only if we are planning for very large range and after sometime we may get bored, unless we could write in the code like in the ardupilot.
So my current plans is to have very cheap system with osd and which could display rssi voltage and try with my existing transmitter  .

I hope you would have already had a closure on the items you need to put up an Eagle Tree OSD system:
1. ET OSD PRO - $65 (all HK prices - the cheapest around)
2. ET v4 GPS    - $61
3. EP E-logger expander - $50

so it is roughly a USD 180+ (well above $240 elsewhere)

if you only need GPS data and basic RX voltage overlay, Remzibi OSD at $120 is the cheapest.

Well if you team up, we could we can drill down more and get better options for an OSD for today, expandable to DIY AP like Ardupilot. I am even planning to integrate few of things to ArduPilot, lest time permits.

And I agree, Eagle Tree has far best interface and expandability (via accessories).

Yes ET looks to be cheapest from hk, but my issue is I need cam, tx, osd and servos all from different site and would have to pay shipping for each seperately