Map Fragments are very much undervalued, even if you're not using them yourself, which I did use an awful lot from lvl36 to current lvl55 have done so many Wots and SFTR bought with fragments has meant that I've had easy adv's on hand for guild quests and events when I've been time poor. and you never know when BB is going to do a crisis over other events.
Should you not have These precious Fragments to hand when suddenly needed, you have several choices the most obvious
1 Buy them but do be aware lots of others are likely to need them as well so price may go up
2 if you have the resources and RPH you can soon whip out some more to use.
3 if you have the resources but no RPH then ask in the guild it's quite possible another member will be willing to make them at cost (providing buff means you'll get them sooner.
4 if you super lucky a guildmate may even gift you some