You can self-publish on many print-on-demand platforms with no upfront charges since the marketplace will recover their costs from any sales that you make. As an example, Amazon KDP currently costs $3.65 for a color paperback 24-40 pages in length and anything after this is your profit. If you wish to pay for a production run yourself however, 100 copies of a 24-page comic will cost several hundred dollars which is not competitive with a print-on-demand service in small runs such as this.