The safest answer would be the kinda things he could get at a Panem version of Best Buy. Computers, food replicators, blenders etc. Things a consumer would get ahold of. If he started buying a lot the Capitol might turn a wary eye on him.

If you wanna use anything specific (like IDK a geiger counter) messages me and I'll let you know. Since he makes science "things" idk if you need anything particular. Sarah is making a science "thing" for her carlos costume, inspired by you btw.