A second-rounder for Foles feels dead on to me from a buyer's point of view.
These are the scenarios I see for Foles:
1.) We re-sign him immediately, he's everything we hope for, and while awesome, our cap structure has instantly become the same as teams with Star QBs.
2.) We re-sign him immediately, he doesn't repeat last season, and our cap is totally screwed for a few years.
3.) We trade for him, start him, he's awesome, and now we risk him being a 1-year rental or having to franchise him and our cap structure is again the same as teams with Star QBs. 4.) We trade for him, start him, he sucks and we let him go, losing our compensation for nothing.
That's a lot of risk for the buyer to take on. Compare that to one of the potential 6 first-round options at QB, where they are either awful and you let them go, or solid and cost-controlled for 5 years to use the $$$$ to build the team around them. Plus, Foles will give you 5-8 years, while a first-round QB could potentially give you 10-15.
I get that Foles had a great playoff year, but he hasn't exactly proven it outside of that situation and I'd rather take my shot on a rookie unless the price is right on Foles.
If I was the Eagles, I'd probably just keep him over a 2nd rounder, so I'm not sure a deal will realistically get done.