I agree with your main point that Faulk would be more costly to acquire, but that top 10 pick and blue chip prospect brought back Stepan and Raanta. A good comp for Raanta would be Cam Talbot, another goalie who looked ready for a starting role after putting up good numbers behind Lundqvist. Talbot and a 7th brought back a 2nd, a 3rd and later 7th. Let's call it a 2nd and a 3rd. DeAngelo was worth a 2nd when the Coyotes acquired him and probably improved his stock a bit in the interim, so let's call his value a 2nd and a 3rd.
That basically means it was DeAngelo for Raanta and Stepan for the 7th overall in a relatively weak draft. It's close to what the Coyotes gave up for Daymond Langkow (a 2nd and a 1st), and he should provide comparable value.
Faulk is a dangerous offensive defensemen, but he's not in OEL's tier. His shot is better, but everything else is a little to a lot behind OEL. Given his contract and Carolina's depth on D, I think they'd be willing to part with him for a fair price, one that's not too far beyond what the Coyotes gave up for Stepan. Schenn and Goligoski doesn't come close to getting it done, though. You're probably looking at Duclair and next year's 1st, at least.