Lol, I'm not sure my method for getting a lot of shards would work for you with such high level crafter classes in all of them.

I started off just getting Goldsmith and Leatherworker, and for a while I had all the shards I needed.... riiiight up until about level 30 I started depleting my reserves. I mined them for awhile (selling shards is great money in the auction house too!!) but than I remembered when I started off my crafting classes they give you a ton of shards to begin with.

So basically I just went and got EVERY crafting class in the game and leveled them all up to 5. I believe you still get shards up to the level 10 quest for each craft (could be 5, cant remember) but yeah. Now I have like 1000 of every shard from doing all those quests. I'm sure by the time I hit the level your at with my crafting classes I will be in the same predicament you are in. Other than this method, the only quick way to get them is by gathering them. Haven't messed with botanist, but miner gets 3 wards that increase yield for 3 of the shard types, i imagine botanist gets the other 3 wards. High GP cost, but if you use the ward on a gather site that has increased yield capacity, that boost helps out quite a bit.