You might find plastic wallets make it difficult to annotate the scores, though they have the advantage of being able to hold sheets back-to-back if your printer doesn't do double-sided printing (and you can't be bothered to print alternate pages and then turn them over).
I use a comb-binder (and print on both sides of the paper). Comb-binding has the advantage of always laying flat. In fact I have copied scores and comb-bound them where the originals refused to behave. Other advantages are; no sag as the pages are bound along their entire length; each score can be separate from the rest and only as big as it is (with ring binders you either have an inch thick file for a four page score, or you keep lots of four page scores together in a ring binder which might be problematic if you file your scores by composer).
The machines are relatively expensive but I got mine for £50 in an office supplies sale. The combs are cheaper than plastic wallets.
Best wishes
barry
QUOTE(Dulciana @ Sep 12 2007, 11:28 AM)

QUOTE(petrat @ Sep 12 2007, 10:59 AM)

I use folders from Asda at 37p a time with clear plastic sheets inside. The pages turn very easily but they can sag a little.
Thanks! I'll give Asda a go!