NPC's don't sell them but players do.
Check the guild trader NPC's in any major city and you should find some reasonably competitive prices.
The number you found for two hours seems very low. If you're not already try farming nodes on Bleakrock or one of the other starting islands, there are a lot of nodes in a smaller map. You need to compete with other players and sadly some bots but normally I can get a good haul without too much competition (PC EU).
Lastly the anniversary boxes can give them out right now, so you can always go and do some dailies and hope you get a few from those boxes.
In the future, please don't leave things in the nodes - it keeps them from respawning(and if you don't want the resin/worms/crawlers/regulus, others do and will pay for them)