Agreed.
As for a Cheap COIN aircraft, surely it all becomes dependent on the threat being encountered in the age of Manpads, cheap to buy may be attractive, but survivability becomes the key, armoured pilot tub, triple redundant spars, high wing protected engines and a semi retractable undercarriage are all traits the A10 had built in from the start, one does wonder how well a Tucano will stand up to any such punishment, cheaper they may be but if they are vulnerable is it cost effective?