Since it does not require ink, a thermal printer is also more economical. The only thing you have to spend on is the paper itself. Thats why a thermal printer is perfect for business use.
Plain paper faxes now have saturated the market and the prices have dropped so low that anyone can afford one. With rebates you may even get one for free. The only problem may be that you may not be able to afford the supplies that go into them. Laser, inkjet, and thermal transfer rolls are the options that you have. The cost per page varies but believe me when I say that the money is not in selling machines, it is in selling supplies. You can shop smart though and look at the cost per page. This is the price of the toner or supply divided by the supply yield. Spending a little more on the machine for a lower CPP can save you a bundle of money.
Thermal fax machines were the ones with the long roll of paper and each fax would be cut to the size that is transmitted. You could make some cool banners with those things because you could set them to not cut and it would continue to spit out the paper! They were pretty much bullet proof. The major problem was the paper. It would curl...