Well, he could use just some of the basic set up for brewing potions, of course. Different sized cauldrons, bottle brushes and a good coarse cauldron scrub for cleaning, a cauldron stand. He's been making due with some of the pots the Sherwood group uses for cooking, and that makes no one happy. Several cutting boards, a good reliable brass scale (he has a small one, but he moans that the calibration's off). And do you have a portable fume hood by any chance?

Plus the basic reagents and ingredients you'd find in the basic school potions kit, through N.E.W.T. level, whatever you can spare. He'll have to order any extra special ingredients.