I looked around at the stuff in stores near me and online at amazon and equated the cost of things per square foot of painting surface in search of the cheapest practice around. I recently started painting traditionally (started purely digital) and am really feeling the pain of bad paintings on my wallet. Each failure currently costs me about $2-4.
The materials below dont account for the cost of primer. The prices also very by size, but generally the medium sized surfaces are most afordable. (medium is 12x16 to 18x24 in inches)
The List of Materials and their prices per square foot. (it doesn't matter if you dont know what a foot is the ratio of cost to surface area remains the same. The lower the number the better.)
Hard board (fine plywood like thick cardboard with a hard coating on one side.
0.46875 on average, 0.3125 at best
Water Color Paper
0.4655
Fredix Canvas Pads (as per Anon's reccomendation)
1.0313 for most of the big pads and 0.9157 amazon's choice
Unstreched Canvas by the roll and thinly primed
1.0263
Arteza canvas Panels
1.5104
Didnt want to type up the scratch page.
I took the cost and divided it by the area.
Cost / LxW
I buy pre-cut mdf panels. 5x7 inch is like 5p.
Gesso them with 2 coats of acrylic primer. Ready within 24 hours to use.
If your pic is a failure, scrap down down any lumpy bits & use it again when dry.
If you're painting in acrylic, then it's easy to just paint over anything you don't like.
BTW, I also paint in watercolour. Use Bockingford which is cheap. The thick Bockingford for when you're flush and/or your work is getting worth the outlay.
Arches wc paper has gone right off. Saunders Waterford heavyweight is the bees knees.