If you were to go by the book the rules of golf are pretty strict about prizes for amateurs though and cash can make people do funny things if you get me. From what I've seen in some society comps with good prizes it would need to be a very trustworthy group. If they aren't I'd recommend using a draw to select the fourballs and break up any conspirators.
One society tends to have golf equipment as prizes and has an arrangement with the local golf shop that supplies them. Unwanted prizes can then be exchanged for other items or credit is given in the shop. Vouchers would be a better prize as equipment is such a personal thing although the prize table wouldn't look quite as impressive with a load of envelopes on it.
The other has a range of stuff from weekends away to crystal etc. A lot of stuff that would basically help keep HID happy and probably help the winner justify playing more often instead of going on that shopping trip. Not so good if the majority of members are single though.
How about a 2 ball voucher for a high end course.
Bottles of booze make great prizes for longest drive or nearest the pin and if got from the local pub can usually be exchanged for the players preferred plonk. A sleeve of quality balls can also go down well for minor prizes.
