Yeah definetly reasonable, makes me want a viking seeing that beast. 125 a tire isnt bad for 29.5 outlaws let alone with wheels which are probably worth a 100 if sold separately. So long as theyre in good shape i say go for it.
What do those tires run new? Wheels are 125 max in my area. If the wheels + discount on the tires is worth it to you I’d say go for it. Even if it is a good deal I’d still make a counter offer, though. Worst case is he says no and you buy them at his price.