3M Scotch Permanent Glue Sticks 8g x24 Pack
Costco £4.79 incl VAT (Farnborough store, but should be nationwide)
Apply at least 2 strokes
Cheaper than eBay and Amazon. Works out 20p each, so major savings against Pritt (which is still the best).
Bit harder than Pritt but bonds very quickly. Make sure you get position right first time.
Acid-free so good for photos.