Powersources are primarily purchased in The Buried Sea and in Katta Castrum off of
Trader Vallarines for Orux, the TBS specific alternate currency earned through doing progression missions or purchased from other players in the bazaar. These powersources are listed under their vendors as "Energeians" because they are a variety of "energeian orb" whose power level depends on your faction rating and how much you're willing to spend. You can also, if you are able to complete some raids in Solteris, purchase raid Energeians whose benefits can be found
here.
Now, Infusible simply means that having an energeian orb will increase or decrease your stats based on the quality and type of orb you use, for each piece of infusible armor. If you have 3 pieces, your stats will go up and down by the amount specified in the orb's type and quality for each piece times the percentage of purity (30 purity = 30% purity). Say it adds 10 Str and 15 HP after purity mod, you get 30/45 added for having 3 pieces of that quality. I haven't had the most time to play with them, but if you want a good look then check out Latan's page, he's great for info and he posts quite a bit on Alla.
I may have left some stuff out or possibly even gotten it wrong, I don't have the most experience with these as I'm out of Orux and still needing to outfit 3 alts with Katta spells. (looking at needing thousands of Orux yet) If anyone has corrections then
please don't let me misinform someone. It will help me as well in the future.
Recap:
Latan's merchant guide (some description of Energeians related to their merchant.)
Latan's Raid Energeians (Stats based on 75 purity armor for the raid quality powersources.)
EQWiki's description and stats of normal energeians. (contains a link to Latan's raid stats at the bottom)