The Vesta comes with 2 Aux. Phaser DHC's. Where can I get more?
I don't see them in the exchange or crafting.

If you only bought one Vesta you have to take the cannon off of it, discard the ship, and then claim a new one from the Z-Store. Once the ship is purchased it doesn't cost anything to claim a replacement from the Z-Store.

You can do that with almost all C-Store ships btw...

So if you have a given console you'd like on your Vesta ship, simply go to the C-Store and re-claim the ship, get the console and then drop the ship again.

Note that certain console only apply to certain ship, such as the Armitage Point defence console

indeed, if you are too... cheap to buy new weapons for your ships at level up if you have the TOS connie, you can claim/dismiss thhe ship plenty of times to get the free leveling phasers it comes with. while not the best, they get the job done and means you can sell most your found weapons as loot, unless your looking for something other than beam arrays to equip on your ship.