have had a similar problem here and had to resort to paying for Gresswell's self adhesive labels (which I don't think much of - they're very flimsy and the pocket is rather narrow). But there are a lot in one box so I suppose they will last some time - probably still have some left before I retire !!! . For labels, I have been buying blank stiff card and cutting them to size. Fiddly but cheap. I'd be interested in hearing about any replies you may get that could solve these problems. I did think of trying to produce some on the computer but am then stuck with the problem of how to stick them in the book without resorting to using Prit-Stick.
You could try GLS though I don't know if they are cheaper www.glsed.co.uk tel 020 8805 8333
you could try a company called BGU - we've used them for a couple of things where they've been cheaper than Gresswell's. They are £10.14 per thousand - getting cheaper the more you buy. http://www.bgu-man.co.uk/ [log in to unmask] 0115 986 2460. They do book cards, too.
We had a similar problem but we DID want self-adhesive labels. Because the stationers were so expensive we started experimenting on making our own. We simply created a template with the appropriate text and printed our own on A4 label sheets
Try Librex (Librex Educational Ltd, Colwick Road, Nottinngham NG2 4BG
www.librex.co.uk) tel: 0115 9504664.1000 label pockets £11.49