I've been making bunting using pages from vintage books - these are mainly Ladybird. String is provided. All you need is a glue stick, and a few minutes of time (preferably with a cup of tea and some cake!). The flags are not attached to the string when you get them. This means that they're more flexible - you can have them all on one long length of string or on a few shorter lengths. The number of flags vary according to the number of pages in the book so the prices vary.
In case you're wondering, I don't destroy really good books - I only take apart those that have been spoilt by an over-enthusiastic reader or where the cover has been damaged over time. If the cover is still useable, I usually make notebooks from them!