At the risk of catching sht for being negative , I do not buy overstruck coins anymore -- they are just too damn easy to fake. Provided this thing is original -- $1200 would prob. be a good price to sell it. I would not be surprised if it went for $1,500, given the fact that a nice collectable example (XF+) would be well over $5,000.
I, personally, would not like to pay more than $500 -600 for it (if original), but everyone knows I am a cheap bastard. My reasoning would be -- this is not a nice enough coin to be proud of, as a part of my collection. But, at a certain price it could plug a hole untill I find a collectable example. Then, the price should be low enough, that I would be able to unload it easy. If you pay $1,200 for it, it will not be easy to unload it fast.