is there any problem with sell bitcoin with paypal? any risk?
Detailed information about the risks of using paypal for bitcoin transaction can be found here
But what if I ship a paper with private keys and post tracking number to auto win dispute?
Incorporating PP as a Bitcoin exchange option have been discussed in depth on this forum. I even have suggested a way to circumnavigate around the issue to no avail. It truly is a dead end.
Aside: I do like your sig idea (Your link here from 0.01 BTC ~~ Two links available from 0.01 BTC) .01 BTC per 100 post per month. Once you reach 200 posts, the rate increases to .02 BTC/month. Of course it would be based on how your posts are perceived by the one who wants to advertise in your sig. I'll go one step further. What if you, or any other person, has another forum account and say they currently have 1000 posts. That would equate to .1 BTC/month to have a link in their sig.
If this is a good idea, somebody please start another thread to have it discussed.