It depends on what time of day you want to golf. If you want to go early in the morning (before 10:00 AM) you probably better off purchasing the 2 round deal on Disney's web site -
May - Oct Rates for resort guests -
Weekkday $89, Weekend $99 2 Round Pass $140
If you buy the membership and golf before 10AM, the 25% discount on Weekday rates each round would be $66.75
4 rounds (2ppl, 2 rounds) would be $267 + $50 (membership) = $317
4 rounds with 2 round pass = $280
If you play after 10:00 am and get the 40% discount it would be
$53.40 * 4 rounds = $213.60 +$50 = $263.60
I would check the math to make sure, but that should be pretty close.