there is no problem with buying gear on Hel. Nearly on every camping between Wladyslawowo and Chalupy you will find some shops or distributors of most major brands, like Naish, North, Cabrinha, Best, F-one. If you need some accomodation and have not made any reservation yet, you better take some tent, because the school holidays starts this weekend and tons of folks will arive ... Good luck!!!