Very hard to find these days and perhaps appealing mainly to western comic completists.
These Western Library comics are text stories throughout and for the first 70 issues there were no illustrations. From #71 it proudly announced on the cover "Fully Illustrated" which meant black and white drawings every few pages.
Individually they would be a few pounds each and more, of course, for early issues and higher conditions. Being text only though there may be less appeal than for full comic strip series like Western Picture Stories.
In 1985 pubisher Ron Phillips produced a 2nd series of reprints starting at #1 and lasting 28 issues. These sell for a pound or two usually.
In 2009 Comic Book Postal Auctions sold a complete set of 110 issues in ten bound volumes for £308, the only time I have heard of a set being sold. A complete set today? If it ever came up, perhaps £500 but how many collectors are out there wanting this title?
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.