Innovations do ones where you can lock it so if you don’t use it all it will keep the pressure. Have had it last for weeks with still pressure in the cart.
LBS will be very expensive in comparison to online like co2cartridges, especially the price of cartridges.
p.s. Look for inflators that take threaded carts and without needing a container for the cart (though they may come with one). That means you can use any size cart and not limited to what fits in the cart container.
Also… wear gloves! You can get very nasty burns off carts as they freeze during use.