I'm going for both the gourmand && bookworm achievements with my pet Raize.

Is there a list out there that shows the cheapest foods and books to help me get the achievements faster?

You can use the website Subetalodge, it can sort items by price, sometimes it's a little inaccurate, but it's the closest list. Try looking for for items that were from site events, trick or treating during Morostide...

I was beat. :P Exactly what Klassikal said is correct.

Thanks