I would think Estrada, Gray, and Cobb would be the fallback options if the top tier guys (QUintana, Archer, Cole, Stroman, Cueto) proved unavailable or too expensive.
Right, but he's already hit his 1st year of arb so will get expensive very quickly. 7M was probably aggressive given that this would be his first year of a 3ish ERA, but I'd say 4 next year and 7 the following year. But even with 2 arb years left, I'd expect him to get locked up to a deal after 2 years of arb. Note Chris Archer, a similar Super Two player, signed a deal after his first year of arb. Granted, he had a longer history of high-quality performance--but roughly on par with what Stroman is doing.
This is semantics, but I would say less cheap instead of expensive. He'll probably get about 36 million over last 3 years of arb. Comparable free agent pitcher will likely want 5 years 150-200 million. It is money, but I think Astros would be more than willing to pay for that level of talent considering the team construction and contracts. Granted, contract status wilk affect what level of prospects get sent, but this isn't bad enough to say no to any one prospect.
I'm at a point where I'm unwilling to give up any elite prospects for Quintana. Martes, Tucker, Perez, and Whitley are off limits with a deal for him. 2nd tier guys are the headliners now but I'm waning on Fisher as a piece too. I doubt the White sox will trade him if his bad season continues. Their best opportunity was in the off season and it looks like they blew it. He was never consider an elite pitcher in the first place according to deeper metrics. Just look elsewhere. Jose Abreu looks like he is renewing himself. Production is up again. He was in a decline and considered just another player compared to what he was doing a couple years ago. If he continues I would look hard at him.
Not one of the bigger fans of Quintana (well I was before he hit trade block..but it seems the Quintana love in Houston has grown exponentially since he got on trade block), but I would take him for one of those guys not counting Tucker (I know I am probably irrational about Tucker) and supporting pieces. Get him and then trade Tucker with some supporting pieces for a No. 2 guy. That would give Astros a very nice rotation with depth to rest pen.