While moar chips is always better, you are not doomed to always be making change. Your crew just needs to learn to play properly.
I've noticed that my new people are often making change, but my regs never are. Never. Well, almost never. Here's the deal:
When the bet is $3, and the person only has two singles, they need to learn to put up a $5 and just say "call." That's it. Let the $2 change hang. This is easy to learn.
By the time the $3 gets around, there will be lots of white in the pot... when everyone has called, the red chip comes in, two white chips come out. All done. The person who was "out of white chips" has magically done two things:
1. Called, despite being "out of white chips."
2. Gone from having two white chips to having four white chips.
And nobody stopped to "make change."
(If the $3 bet was raised, and it got back around to the person with the $5 up, and they fold, that's when the red goes in and the change comes out - but again, there's usually change in the pot.)
Sure, every now and then change will still have to be made - someone needs four white back, and there's not enough in the whole pot, etc., but those situations are pretty rare.
Also, if your regs get in the habit of using the red chips for bigger bets - instead of insisting on betting stacks of singles to look "intimidating," they won't run out of singles so quickly. Most of mine also try to bet off any chips they start to accumulate in excess stacks... for example, in my $1 game, we use a $.50 frac for small blinds, but I have a limited quantity. If someone manages to accumulate an excess of fracs (more that ten), they start betting a pair of fracs when posting a big blind, or when limping for a dollar, with the expectation that the fracs will occasionally move out to someone else who needs them... thus, avoiding people having to make change, later.
Some people, however, seem obsessed with either trying to accumulate all the fracs - followed by making a bet of $10 with a stack of 20 fracs... or seem obsessed with conserving their highest-denom chip, even when it's their exact bet size. (Seriously? Don't bet $25 by counting out all your singles and fracs, leaving you with exactly one green $25 chip and a frac. Whether you fold people out or get called, you've just wasted everyone's time...)