Hello!
The best use of an Infinity Chest is to hook them up to hoppers that are coming from a farm, whether it be iron golem, evoker, or any mob. All you need to do is place it down and have items from hoppers move into the chest and they will be automatically sold and the money will be put in your balance.
Another question thats asked a lot about these chests, is if you are able to move them once you have placed them. You certainly can; but look out in chat for "Clear lag" and try to video removing them as they can sometimes be glitched, or lost.
Hope this helps!
Madison