Acknowledged, Freya.
Depending on Dancer's repairs from his solo mission, the only other viable option would be Midnight Lance with the Highlander from the unit reserve standing in for the Phoenix Hawk that is still in the shop. Midnight, are you interested in being called in? (Repairing the Highlander could get EXPENSIVE real quick.)
I'm flexible about being called in, whatever's in the best interest of the unit. Midnight lance at full strength and current mods is BV: 4068, so only 70% of available BV. The Highlander, Wolverine and Clint are 4,288, so slightly better than Midnight at full strength. If Midnight's selected for a mission the opponents BV should account for him being short. As a reinforcement lance you'll just need to keep that in mind.
In terms of expense, it really all boils down to salvage. After salvage from the last mission Midnight was net -70,000 not including the bonus 25,000 for the elite mech tech. Plus or minus 100,000 on a mission I'd say is safe to call a wash. The number's probably bigger than that, but it's certainly within it. If salvage is sufficient to cover the damage then it's more a question of how long do you want it to be unavailable? I can replace the heat sinks, 2 MLs and SRM6 ammo. Everything else including the armor is a custom order.
Now, alternatively you throw just my 2 mechs in and don't risk the Highlander. You get some extra firepower and while Midnight takes a risk, the unit as a whole doesn't. The two mechs together are ~2,000 BV.