Sorry to revive an old thread, but the math was bothering me. The square roots are correct, but you don't multiply them by 2000; you multiply them by 1000, then x2 for the slotless feature.
"..The easiest way to come up with a price is to compare the new item to an item that is already priced, using that price as a guide. Otherwise, use the guidelines summarized on Table: Estimating Magic Item Gold Piece Values."
"Save bonus (resistance) Bonus squared x 1,000 gp"
RAW.
So:
+1 = 1^2 (bonus squared) x 1000 (Save Bonus Multiplier) x 2 (Slotless/No space limitation feature) = 2000
+2 = 8000
+3 = 18000
etc
That is total Market Price. You pay half that for crafting.
Also, the discount of 30% or 10% can only be applied once each (for, at best, 40% off) and it comes from the Market Price. So a Tattoo of Mind and Body +1 that requires the user (person who has it on them) to be a Fighter with a skill of Heal 1 Rank = 1200g for the market price. (600g to create)
Can hook up with references if need be.