They foind my listing on ebay and said they were sending me a check for $2800.00 more than my asking price because they were going to text me instructions on where to send $2700. And the $100 was for the sending fee but i would need to do that before cashing the check and instructions wouldnt come until i confirmed i got the check.

Total scam.  Do NOT cash that check.  Instead turn it into the post office so that the postal inspectors can take a look at it.  Common scam.  You deposit the check, send money to whoever they want and later the check comes out bad and then you are in hock for the amount you might have used.  Stay away from those kinds of deals.