Buddy, you're not going to sell your Linden's for more than market rate. Sorry to tell ya.
USD/SLL current is 241 and you want 260.
He's offering 260 SLL/USD, which is a better offer than 241 SLL/USD.
Linden Dollars should be quoted as Dollars per 1000 Lindens. It's much easier.
1000 / 260 = $3.8, which is cheaper than 1000 / 241 = $4.1.