I had quite a few meetings where I couldn't come up with a dollar either. Nobody ever gave me a hard time. Give when you can and don't fret about it.
You know, if you give back your copy of CTC and let them sell it to someone again, you could contribute in that way. Or bring treats if you can - or clean up before/after a meeting - or organize the pamphlets - or something. Some people have money to give, some have time, some have skills. Just do what you can!