Issues of this title turn up on eBay UK all the time though not often in high grade. The Doctor Who strip is hugely popular as it's the culty Jon Pertwee incarnation. Issue #3 is sought after for the Jon Pertwee cover. The free gift Space Wall Poster plus stamps in #1 adds £35-£50 to value. Significant value increases in recent years.
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.