So I'm going between different shop keepers getting them different items they ask for... but do they ever ask for a different item? Because I just got an item worth a couple million and I'm not sure if I want to spend that much.

I think you're stuck with whatever item they ask you for, but all of the options can be restocked so you can either spend a few mil on it or watch for a restock, whichever is easier for you.

I didn't have repeat items so odds are you'll be fine to proceed

Thanks, I just went ahead and bought the item. The rest of the items weren't nearly as expensive.