So yes, I would try and get a handle on how much your players are willing to lose in a night for the sake of "entertainment." Divide that number by 300, that's what the big blind should be. If $60 is their limit, then 0.20 or so should be the BB. If it's really only $30, then 0.10 should be the BB. Once you figure out the BB, then figure out the min and max buy in. I think 20x BB is a good minimum for NL play, 100x-200x is a good maximum depending on if the players enjoy deeper play or more all in situations.
So you could do 0.05-0.10 blinds, $2 minimum, $20 maximum.
Players buying chips (whether starting from zero, or adding to an existing stack) must remain below the table maximum. The only players with stacks above the maximum should be those that have won chips. Those players cannot buy more.
Rules that involve the maximum.
*Most chips a player can buy when starting from zero
*Players that have won chips above this limit cannot add chips (see my additional rule below that you may also want to apply)
Rules that involve the minimum
*Everyone's first buy in must be at least of this amount. (I make an exception that one later buy-in may be below the minimum. If a guy wants to play the last $1.50 in his pocket one time after getting felted, I'm not going to send him to the ATM. But I won't let him do it again without a full minimum on the next buy in.)
*Special rule in my game, any player with chips wishing to add on must add on at least this amount. (Meaning in this example, players with more than $18 cannot add on as $2 puts them over the maximum above.)
Now if this is your game I would suggest getting a nickel-quarter-dollar set for denominations. 50-60 chips per player is my preference for NL play, but it's surely possible to get buy with some less.
So a 600 chip set of 100/300/160/40 of 5¢ / 25¢ / 1 / 5 is probably good for the example game. I would have mostly quarters in play, but just enough nickels to make blinds. You can then make 10 buy ins of $20 with something like 10/30/12 of 5¢ / 25¢ / 1. Any rebuys/add-ons can be done using the leftover singles and fives.