The entire mythic weapon system needs an overhaul. The point of it was to have lengthy time consuming quests to counter the money sink requires to sponsor dynamis and get all that currency for relics.
Now you have a bigger money sink portion than Relic weapons, plus all the other quests. They need to either increase the number of places you can get alexandrite (make it drop off non-salvage gear mobs, purchase with imperial standing, anything), or lower the total needed again. They could lower the needed alexandrite to 5k-10k and I really don't think you'd see a big spike in people trying to get Mythics given the other requirements needed like the ZNM drops, and the Einerjar and Nyzul Island items that also take months to farm.