How should the woman pay for the books as the man suggests?

W: I wonder how I should pay for the books I just ordered?
M: You can pay by check．You can also use your credit card．In that case, you pay two dollars more．If I were you， I’d send them a check．

M: I’m leaving for South America tomorrow．
W: Are you goingwith the group?
M: That means more money. I can manage by myself．
W: But group traveling is safer．And you can enjoy better service．
M: You are right, but I just can’t put up with the fixed schedule．