Ultra Pro used to make pages for phone cards that work perfectly with slot cards. This was one of those times that I could share supplies between two hobbies. The two varieties I have seen are:
1. 8 cards per page, horizontal alignment.
2. 8 cards per page, 2 rows of 3 cards vertically aligned, with a row for 2 horizonal cards.

I'd post scans, but my scanner is down.

I have NOT purchased anything from this site, but here is what looks like a reasonable place to buy books with pages:
http://www.moneycard.com/supplies.htm

If you get or have any phone or money cards you don't want, I would be glad to take them off your hands!