Your batteries restrict how long you can operate things from an inverter and the size of the inverter governs what things can be run at all. To run a 1000 watt coffee maker, you need at least a 1000 watt inverter. One group 24 battery will allow you to run that coffee maker for about a half hour, which is plenty of time to make a pot of coffee.
You need to figure out what it is you want to run and for how long, then figure how many batteries you need to do that with an appropriate size inverter. Identify the appliances you want to use, get their electrical requirememnts from their rating plates and add up the watts (or amp). Watts = amps x volts, so you can convert watts to ampos and vice versa.
12V appliances tend to be expensive as they are mostly specialty products with little price competition. But if you only need a coffee maker, it's probably cheaper to go that way. If you had to buy several 12v appliances, then the inverter is a better way.
You are going to need about the same number & size of batteries either way - the total power consumed will be about the same.