I think you should only be able craft PA in Navarro, Lost Hills, or San Fran. It's not even so much about the player having a high repair skill; it's about having the industrial base and being able to hire specialists who can do the machine tooling, the miniature nuclear reactor creation, the special alloying--it requires an assembly line backed by resources and financing.
Now for servicing a damaged suit of PA, an individual with a high repair skill could probably do this at a wider range of places (any abandoned military base), or perhaps by using a field repair kit.
For parts make it like base construction; you can either "Rush Buy" the PA for some large bottlecap amount or you can just pay for the assembly line and scavenge for motivators / parts from wrecked suits. None of this dismantle crap either, just have parts randomly spawn from PvP corpses, or just have dead soldiers in base quests / random encounters which date from the "civil disturbance" era.
I'm thinking a 25k BIN and 10k for DIY would be reasonable for a piece of basic PA (not Advanced). And to anticipate the argument that one person will farm this or abuse this horrible condition of PA being available, I say to that statement "Take your head out of the sand!" Start thinking of the average user and how PA is a big reason for playing Fallout in the first place. At any given moment I can get killed by a single shot from a medium-tier weapon, but all the things that worked in the original game-balancing like AC + decent DR/DT have been removed or made inaccessible for no logical reason.
Seriously, think how childish it is to play keep away with PA, never mind that the pleasantness or suckiness of any particular game mechanic is an objective truth that will be proven when players decide to stick with, or conversely, turn away from FOnline. Last I checked Power Armor was still appearing on the title screen; and maybe I'm wrong but that tells me PA is an essential part of the Fallout experience, a far cry from being something that is "too much to ask for." This isn't a groundless dissatisfaction, but a core ennui that every player can detect and then list as a black mark against FOnline.
