$1/$2 sounds right to me.

You don't lower the price, but on older games you can give something back to the player by ie giving an extra ball faster.
When you have them all set to 3 balls, set these to 5. Or on medium instead of hard settings.

Being an operator is a lot about getting to know your locations and what people like. Some games may do better than others.
Sometimes medium/hard settings will make a difference. An op I know made more money when he switched from 3 balls/game to 5.
You have to experiment and see what works and what doesn't. Also replay settings, extra balls, ..

The prices for game is only one factor to change, and one you can later always lower, but not easily increase.
So keep your prices and try to see what other things have an influence and work for your locations.

Usually the price per game doesn't influence the initial coin drop much. People will be curious and want to play one game.
If they will play another game after their first, that is something you need to work on. Give them value for their money and set it just hard enough that they stay challenged and not become bored.
Even at $.25 people may not play again if the game is too hard and they immediately drain. If it's too easy they may become bored of it, and your machines stop earning after a few weeks.