well I found Ultra Set Single Step for $189 - add Shipping & it's $223, cheaper than anywhere else I've found on the planet. and it's cheaper by UPS to order 1 at a time........ this glue is tenacious and get's every where so, I've run thru a bottle of Bostik- Best Ultimate Adhesive Remover already, but it's light years away from anything else we tried. also, we went an extra mile to keep the planks in place. Lowe's makes an Underlayment Seam Tape by "Blue Hawk" that literally "stretches" and absolutely holds the planks in place even w/ my weight on it. Using "Painters tape" to hold the planks is like using "harsh language" to fend off a bear. once we put that tape down that Lowe's makes, we can walk, work, roll and just about dance on the flooring & it stays. is it expensive? yeah - about $5 a roll, but totally worth it to avoid any slippage. the glue however gets on everything, so about 20% of the floor laying is spent cleaning up - but, man - does it hold and the only moisture that's getting on that floor will have to come from the "top-side". i'm sure our slab would be fine w/ something less - but, I don't wanna find out the hard way. Great Suggestion.