Yeah, for 2nd gen legendaries, there is no getting around PvE for various gifts and mats. You see whining from the PvE crowd about having to do 4-6 hours of WvW to get their GoB, but WvW players have to spend far more time than that in PvE.
Alt account here, unable to buy gems. My main account can buy them just fine using the same billing method, so this is clearly an account-related problem Anet needs to fix.