Quote - IMO...He turned himself in so that the reward money would be sent to that guys (brolins) wife. Wade liked him, and felt that he was honestly trying to better his family and himself...so Wade honored that.

It wasn't about the money: by getting into the train, Wade allowed Evans to finally get the respect that he deserved from his son.  Getting on the train at the end, when he could have walked away, demonstrated that.  He'd shown William his father's sacrifice hadn't been for nothing.

Of course, he planned on escaping eventually.  He'd told Evans as much in the station when he revealed he'd already escaped from Yuma twice, which Evans had accepted.  One way or the other, Evans would be remembered as the man who'd stood up to Wade and his gang and kept his word, any subsequent escape clearly not his fault.