Do you have to be a member in RuneScape to get a skillcape?

no you dont. to get a skillcape all you have to do is get your skill lvls like (wood cutting, mining and etc.) and get them to lvl 99. then you get an individual skill cape for each thing, like woodcutting. hope this helped.

Wrong they are members only and you have to buy them for 99k which is a bit unfair though. And the skill dungeonearing can get up to 120 in lvl hope my answer helped.