What's the difference? Whatever you're saving on a trasnfer fee is basically trasnfered to wages. Assuming he'd ordinarily be on about 200k a week, the extra 150k over 4-5 years translates to a 30-40m transfer fee. A little high for someone his age but generally pretty reasonable.
The main issue is whether or he's good enough, and I'd having thought about it I'd have serious reservations about investing so much to someone in a position he's rarely played in a new league just as he's passing his peak and entering his 30s. Nothing to do with resale value, it's just too risky period.
