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I believe that crystals will go up in price when jewelcrafting 500 gets released. Since they sell close to a copper above the vendor price (except for rubies which make a nice profit from through flipping), there is minimum risk in this investment. Sure, you could lose some money having to sell back to the vendors if it doesn't pan out, but what if the price doubles or even triples? It's worth the risk.
Here's a screenshot of just 10 gold's worth invested:
If you need something new to invest in, I recommend the level 65 crafting material crystals.