I just started my first Energy Weapons character and would like to know th ebest place to buy mods. I'd like a fully modded Laser Rifle, Plasma Rifle, and maybe a Gatling Laser or Plasma Caster.

Also, I read that if you shop at the Silver Rush early on then their inventory will never change.

Crimson Caravan, Novac, Old Lady Gibson, and oddly enough Gun Runners... they all have EW mods often.

I found the scope and the focus optics for the LRifle at the dino shop pretty early on. Crimson Caravan is good too.

Thanks, I'll check'em out.

One thing about Crimson Caravan: Blake's vendor container has a habit of not restocking, despite being in the vendor container cell which resets on Sundays and Wednesdays. If this happens you can try saving in front of him and then exiting the game completely (main menu may suffice) and reloading, which should force his container to restock. Note that doing so will reset the game-calendar to Sunday, potentially causing the vendors on the whole to miss a restock date.

Weapon Mod stocking is random, so there's no guarantee you'll get the one(s) you want on any given visit, but between Hannibal's list, the arms dealer (not Alexander, he never has them in my experience) at the 188 Trading Post, the Khans' armorer (shop is in the storm cellar of the trashed house just outside Red Rock Canyon), and Lacy at Mojave Outpost you should be able to find at least a couple on any given pass through the lot of them.