Should I buy 2 year old camera - new NEX 3 at Low Low Price

The differences may or may not be significant depending on your use. The sensor difference in NEX-F3 vs Nex-3 is not mainly about MPs , it is more about improved high ISO performance and better dynamic range. NEX-3 is already pretty good in these areas but NEX-F3 is even better. It also has ISO 100 option which NEX-3 and NEX-C3 lack.

You have already mentioned 1080p and faster FPS. Then we have the new style of LCD, plus support for optional EVF. The NEX-F3 body is also slightly larger, which may be good or bad depending on your preferences. And there are other differences as well.

Overall at 1191 vs 1999, nex-3 does seem a pretty good value, though I have no idea what is a fair market value for these cameras in your market.