Portable printer with battery - Is there any?

You may know, I'm doing a MLM. I go to every individual houses and brief them with my presentations on my Notebook. The problem is, when they join me, I need to generate their ID immediately and hand over them the cash receipt. Most of our clients don't even have a email id, so the receipt can't be sent to them via email. Practically, it's not possible to visit the browsing centres for taking print outs. Currently, I'm managing to ask them to come up to my place. But, as the team size grows, this can't be done. There are some deeper villages, where browsing centres also far away. There won't be even courier service, so mailing the receipt later won't also be possible.