Thanks a lot :) I didn't know that it's possible to do something like that in excel. I will told you how I do it, maybe there is something that can help you.
When users choose their coins, I put coin name in array and save that array in Chrome storage. Later when you request coins informations, I call that array from storage and compare coin names to names in the array that I just called from storage. So, I loop through the data that I grab from coinmarketcap and compare each coin name with the names in the array. If there is a match, I know that it's a coin that user want. It's done almost instantly, because it's not complicated operation for the computer.
Sometimes to grab data from coinmarketcap takes a few seconds, but as they told me they have a plan to lunch premium API, so it should be a lot faster.