I found these World War Toons Sherman tanks from MENG at Hobby Lobby. You can also find them at your local hobby store or online. They run between $7-$15 each.
The aesthetic is very similar to the Hasegawa Egg planes I've been using to make Grot Dakka Jets. The obvious next step was to make some Grot Tanks so I got about building. Unfortunately I forgot to take WIP photos but I do have this before/after example to give you an idea of the work I did:
MENG makes several variants of these tanks and they all share a toony quality. I used a few bits and a bunch of styrene scrap to convert the tank. I also used greenstuff to make the weld lines. The model was airbrushed with Vallejo paints of various tones of red and detailed with Vallejo acrylics. Most of the metallic were achieved with graphite powder. After the painting was completed I washed it all in oil paints and sealed it with a mat finish and touched up the graphite areas.