The average minimum OPENING deposit is $100 bucks.
Monthly service fees... it all depends on what state you live in.
Those fees can be waived, however, with a minimum balance or a direct deposit. It depends on which account you go with. Each account has it's own detail: ways to waive the monthly service fees, the minimum balance, the minimum amount for a direct deposit.
It's one of those thing where you'll have to go to each website. Look at their checking accounts. It'll ask what state you're inquiring about. And then all the information is displayed.
There is no minimum deposit, only a minimum to open. There is a minimum monthly balance, if you want to avoid fees. They do make their own rules. They are all a bit different. If you are worried about getting the lowest cost account and don;t have much to keep there, check out some local credit unions instead. They are generally cheaper.