anyplace you can buy wine will have a box of cheap corkscrews at the checkout counter.i would go that route rather than look everywhere for a knife with one built into it..i don't think i've ever seen a pocket knife that had a corkscrew that any guts to it..
The corkscrew in my Victorinox made
German
Army
Knife has never failed me. AND it only cost me around $6 from the good folks at the SOSAK.