Haggling!
They don't show any interest in the contraception spell - everyone in Montréal goes in for (usually) reversable sterilization before they arrive at the Scholomance - and sadly none of them know Spanish, but a few of his earlier offers do interest them. The antitoxin, for one, and the envelope shield, and Alexei wouldn't mind going over their healing spells for any gaps, upgrades, or differently advantaged ones.
It transpires that a lot of the sword spells are in Japanese, but he has a few for trade, sure. The nicest ones are pretty mana expensive, of course, but he has a force multiplier, a sharpening spell (which is actually more maintenance than combat, really) and one that heats up your blade, though overuse of that one can damage the weapon (which is why he rarely used it at home, and expects to roughly never use it here).
Does he know how precisely the stimulant spell matches, say, Adderall in effects?
Their reflexes spell is somewhat long, but it's efficient, and Alexius is welcome to any two of it and/or any of the others in return for the antitoxin and envelope shield. They're also, definitely, interested in the memory potions, if they work as well as he's suggested they do.
"Do you have any recipes for... Growth," Alexei asks quietly after outlining this, his eyes lingering on Angie, who's chatting with Zed a short way away while they keep watch on the room and the crowd. She really is very short, and perhaps distressingly skinny (but then again, a fair number of the freshmen are).