Don't stress about Invention Origin enhancements yet. I'd suggest sticking with Dual Origin and when possible Single Origin until you get a bit higher up. IOs are great in that they don't stop working as you level but they also don't increase in effectiveness.
SOs can be bought but also earned. Doing the Death From Below (DFB) or Drowning in Blood (DiB) trials which can yield 4-5 SOs per run for low level characters. (you can also a bonus at the end, up to 4 unique, one per run)
Here some more info:
https://paragonwiki.com/wiki/Enhancements
"There are four main types of Enhancements: Training, Dual Origin, Single Origin and Invention Origin (abbreviated to TO, DO, SO and IO respectively). There are also several kinds of Special Enhancements, usually as rewards of a particularly difficult task set to players. Training, Invention Origin and Special Enhancements are usable by any character. Dual-Origin and Single-Origin Enhancements are only usable by characters based on the character's origin."
"Single-Origin Enhancements
Single-Origin Enhancements, often referred to as SOs, are even more powerful. They provide twice as much improvement as DOs (or four times as much as Training) and may be used only by a character whose origin matches the Enhancement's.
Single-Origin enhancements may be bought at origin-specific stores and NPCs in various zones and, at an inflated cost, from individual contacts. Currently, the lowest level Single-Origin Enhancements generally available for purchase are level 25, which are usable by characters of minimum level 22. There are, however, some particular exceptions as low as level 13 sold in Mr. Yin's store, allowing some characters to use some SOs as early as level 10. SOs are dropped by enemies for characters of level 22-50. SOs are also sometimes provided as mission bonuses, and in the cases of Task Forces and Story Arcs, the player may even choose the aspect.
SOs in certain level ranges for Heroes may only be purchased from contacts that require a mission before they will deal with you. Here is a quick reference. More detail in each contact's page and on the Stores Inventory page.
Origin - Contact Name - City Zone
Magic - Serafina - Brickstown
Mutant - Penny Preston - Founders Falls
Natural - Agent Six - Founders Falls
Science - Holsten Armitage - Brickstown
Technology - Mark IV - Founders Falls"