If you want to paint one: between $5.00 and $10.00 U.S. in materials - it depends. Naturally, you can't really buy stuff for just one piece, so there is an initial investment. Mine was in excess of $1,000.00 U.S., but 1/10 of that can get you started I suppose.
If you want to buy my finished, varnished artwork: I sell the small ones (30x40 cm) between $50.00 and $150.00 U.S. plus shipping. (Resin finish slightly higher.) I would accept the equivalent in SBD from Steemians. Unfortunately, if you want to buy this particular piece, it's sold already. Sorry about that.