I had an MSC accept an offer to do a shop for mileage plus their fee, which was already pretty good. I don't even think it was a rush, but it was in a remote location as it was a "hotel" shop in the middle of nowhere because it was a cabin. Didn't require a stay, but I said I can travel here for mileage reimbursement, which was 100(ish) miles in each direction, and came out to an additional $120 or so on top of the shop fee and they didn't hesitate to accept it. Literally I heard back from them within 20 minutes with a yes.
That being said, I didn't take it, because of other things going on, mostly because it required a $200 or so OOP and I just couldn't front it. Now, I'm sort of feeling like maybe I could have upped that fee a bit. But, that being said, when I said I simply can't do it right now with the holidays they were very happy to say come back and do some shops for us after the holidays. So, the mileage for that one apparently didn't even make them blink.