See also Dandy Cartoon Book. Sub-titled: Comic Library Special.
These seem to be fairly common on sites like eBay UK. A quick type in of issue #1 today (28/4/2013) brought up three different copies of number one for sale. The key is to make sure that none of the puzzles are done. If they are and depending the extent to which they have been done then a significant decrease of value follows. A couple of puzzles done you'd think half the values listed here. Lots of puzzles done then practically worthless.
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.