I'd say feel him out about Greek Life to see if it is something that he wants to do. If he can see the benefits of being in a GLO, he will spend the money for it. All the pennypinchers that I have known were the first to pay their dues in full. I guess it's because they didn't spend their money on junk like I did.
He may also want to wait to see what college is all about first. Continue to invite him to things and introduce him to people. Get your fraternity little brother involved and other underclassmen. After all, your brother only has one year in the chapter with you and the rest of his college career with the other guys. OK, I am rambling now. Good Luck!