I have to acknowledge that I am very fortunate to create comic art digitally in the manner I prefer. Most people are not so fortunate. Not that my workstation was wildly expensive; in fact, I built it on a fixed budget (a store-bought or customized rig would have cost me an extra $500). Still, I had to gather raw materials and software, and that was roughly $700 in total (the operating system license and graphics software were previously purchased).
It should also be noted that I was able to afford my workstation due to a steady job that has absolutely nothing to do with comics. In fact, the reason I do so much work digitally is that it allows me to cut corners, as far as time goes. When you work all week, it can take a lot of time to scan individual pages of art, clean them up digitally, etc.
That being said, if I did not have the ability to work digitally, I would still be very fortunate, in that comics can be made traditionally (at least at first) in fits and stretches. If one cannot afford a few hundred dollars to start working digitally, one should be able to get a reasonably decent type of art board, a mechanical pencil, a triangle, a bottle of ink, and a few pen nibs for under $50. If you’re lucky, you might even get a few things on steep discount.
If you’re on a super-tight budget, the hardest thing to do is going to be finishing work for your book. If you’re willing to publish in black and white, you’re going to have it a little easier (i.e., no internal page coloring, most of which is done nowadays in either Photoshop, Clip Studio, open source art apps, or, in some cases, via art programs on the iPad). You will most likely still have to prepare your files for publication, and that means tech will need to figure into your future somewhere…and the only real advice I can give anyone here is to be either very frugal or very creative in how you raise funds for a reasonable workstation (you can do a lot nowadays on even the cheapest iPad, but I hesitate to say that you can easily do prepress on one).
On the plus side, I can say this: if you’re actively working on a book, and your biggest issue is that you’re not sure how you’re going to afford to finish it, you’re ahead of the vast majority of people who “aspire” to do a book and never actually produce one. You have pages you can show people. You have a portfolio (even if you can’t afford a fancy case to hold your pages).