You can swap a treasure parcel for feat or skill training But I can't recall offhand which exact page in the DMG.
You can purchase a PHB spell service casting of Find Familiar, cheap enough to be worth it, regardless of negotiated price. Right there in the basic items list.
Oathbreaker built not at all like SorO's build, can have Warlock 5 for short rest Animate Deads. That's gotta be worth some Necro-ing.
So, just a quick update - turns out the familiar version of an Imp isn't one obtainable with Find Familiar as a spell per se, according to the tweets from creators... but because of this, the Imp can be a familiar without any spell at all. It just has to be convinced to do so. Just FYI for people who don't want to lvl dip or feat dip for one. Just find and obtain one through dialogue! The term "familiar" in the instance used was meant in the "magical companion" sense not the "find familiar" spell sense apparently.
This has the beautiful side-effect of making them available for anyone, of any class and build, all for some in-game RP, or a detailed character background. They act independently, and the character can still get their normal familiar/animal companion/etc if they can obtain one. They're basically an unpaid cohort.