Extra shift pay?  

It did NOT say anything to the affect of $250 plus $250, that's just simply false information your spreading. Its simply a bump from $200 to $250 period not $500 all together. 

In my opinion a relief / pool that requires airfare, rental, hotel, per diem costs more than two pilots combined, more close to maybe three pilots staffed at the base when you figure all of those variables stated above and include salary. "Step over a dollar to pick up a dime" or whatever that saying is.