Using an 8x10 tray and one liter and getting Amidol from Artcraft Chemicals at $185/lb more or less, Amidol comes to $3.25 per printing session. You can cut the Amidol to 6 or 7 grams, making the cost $2.85 to $2.44. In my formula, Amidol lasts a long time--all day--or as many prints as you can put through without losing it due to carry over into the stop bath. Since it should take no longer than one hour (okay, if you are new at it, an hour and a half) to get a perfect print 5 times (unless your negatives are totally off the scale), in a full all-day printing session that's 25-40 finished prints from 5-8 negatives or about 6 cents at very best to 13 cents a print at the very worst.