I had a humorous idea in mind, Googled on Cheap Drawing Software, and hit upon Sketchup.
It’s not for artistic drawing, nor is it a CAD program but you might enjoy trying it out. Sketchup6 is free, Sketchup Pro is $495 or thereabouts.
The tutorials are extensive. It might be worth a look.
I love Sketchup. It’s a little awkward at first, but I’ve found it to be intuitive (once you “get” the program). It was pretty useful in planning out and rearranging the furniture in my rooms. I even used it to plan a concert - it made visualizing the stage and seating and communicating that to the facility straightforward, and fast.
If you’re looking for other options you might consider GIMP
I did, and it looks pretty formidable. Is it?
Inkscape is pretty damn fine too.