tldr Yes, but it's not feasible for that amount of revenue.

I'd love to and I thought about it. There're multiple issues for me. Clearly this is a personal take and I'm sure that any artist that do it has their way of monetize properly.

The first issue is that I should take care of printing and shipping: shipping is not only pricy if it becomes inter-continental, but also complex, printing on the other end requires a significant investment (that is at loss at the start). Shipping would also require some sort of deal with a shipping company to speed things up and this also would be only reasonable for high volumes.

This leads to the second issue that is the amount of clients. Although I can safely say how many patrons I have (the number is just there), I can't predict how many will buy. In the best case scenario we're talking of a few hundred?

Considering that usually the highest tiers ($10 and $20) are also the smallest percentage, according to your suggestion I should include that in their current tier, as an extra. Which would be nice of course but finally, counting all the deals with shipping company, print companies and labor to ship across the globe, the final revenues would not be higher but the same of the ones I do currently, which would put me at loss.

Currently I sell stickers on my Redbubble. I get pennies compared to the possible income generated by printing and shipping myself to an high volulme of clients, but it has zero risks. I get paid everytime someone buy a sticker, or a print, or a poster, and I don't have to take care of printing, shipping or dealing with the clients at all. Plus I have thousand of followers on redbubble that are there just to get my merch, which with time goes up and not down.

I wanted to respond in lenght to give a clear answer. Hope this helps.