If i remember correctly Sunderland matched what we were paying Grigg in the Championship to get him to sign for them in the league below, so any loan deal would require someone taking on a large wage (or decent percentage of it). My guess would be based on other players at the time in the squad Grigg would've been on something between 5-10k.
We are limited to paying 1.5k a week, which will probably be nowhere near enough to tempt Sunderland into doing a deal unfortunately.
I imagine Grigg would fancy coming back and we'd obviously like to have him back right now. But while we are in Admin i can't see it being possible.