It's something we discussed at launch and opted not to do, sorry. Itch offers no way to automatically split the income between the three developers, so making the game completely free simplifies my accounting and avoids the need to send money between us.
I'm honoured that you'd want to pay us! If you're particularly eager to send us money, our various Ko-Fi and shop links are listed on DWC's page. But really, the best way to support DWC is to share it with friends :D