To me it seems the easiest change would be adjusting the ammo.

Bulk: DAM x 0.75, TARGET DT -5, CND x 0.75
Same cost.
Base: TARGET DT -10
Cost doubled.
Over: DAM x 1.25, TARGET DT -10, CND x 1.25
Recipe materials doubled.
Max: DAM x 2.00, TARGET DT -30, CND x 2.00
Recipe materials tripled.

What are we fighting for in New Vegas? Hoover Dam and HELIOS ONE. What are they? Power Sources. Power is key in rebuilding America, it makes sense that portable power would carry a premium cost, but, it's worth should match the cost.

These changes make sense both within the context of New Vegas' story and Energy Weapons previous state in Fallout; Rare, Expensive and Powerful - Just shift that philosophy to the ammo for a simple solution.

What?

Looks good and I am actually using something very similar, but I don't see the need to increase the cost.

Epic Gauss Rifle is a go...

Energy weapons should be devastating but costly as hell to feed. We're talking about Lasers and Super-heated Plasma powered by energy sources the world has long since lost the capability to reproduce.

Energy weapons aren't broken but a base 8 cap per laser shot for a boost to AP when it's really only needed on 10 - 15% of enemies is quite steep imo.
It's not like most EW can't one - two shot kill most things anyway, I've killed every deathclaw on the map at least 10 normals just with a normal charge modded laser rifle.
Making ammo rarer / more costly and damage higher is not the solution, as most already consume hellish ammounts and repairing is more awkward imo.

Seems a little too powerful.
I'd rather just go with laser weapons automatically having -3 to -10 in DT depending on what weapon it is. (Laser pistol -3, RCW -2 (for each shot), Tri-Beam -7 (For each beam), Laser Rifle -5 etc)
And then plasma weapons automatically eating away at DT with each shot depending on the weapon. (Plasma Pistol -1 DT for every 3rd shot, Plasma Rifle -2 DT for every third shot, Caster -1DT for every 3rd shot (it already have a lot of dmg) Multiplas -1DTx3 for each shot. (to make up for it's incredible ammo consumption))
I don't know if this would make them too poweful but the weapons should have a negate DT automatically, I mean come one, they're lasers and plasma, not bullets but pure source of energy.