I would want at least 3 years left for any pitcher we get in a trade. I still think one of the young Astros starters makes the most sense. The Astros were interested in Mullins before to upgrade their center fielder. Elias knows that system so I like that as advantage. Garcia, Valdez, Javier and Urquidy would be better fits because of at least 1 more year of control. Javier would be my first choice because he has more strikeout stuff compared to other 3.
The Reds got two top 50ish prospects in Marte and Arroyo, plus two other solid prospects, from Seattle for 1.5 years of Luis Castillo, so 2 full years of Burnes or Woodruff (who have both been significantly better than Castillo over the last 3 years) should cost even more than that. Something like Cowser and Holliday, plus 2 or 3 more decent prospects from our top 30.
Personally, I'd rather just throw a Brinks truck or two in Justin Verlander's general direction since our payroll is sub-Rays level atm.