difference in wood flooring adhesives

I happened across a really good price on some Harris Tarkett 9/16" unfinished 5-ply engineered white oak 7" wide planks. The planks themselves are a bit on the short side, about 2', hence the great price of $0.99 / sf.
I'll be gluing this down to a concrete slab in Florida. The manufacturer, of coarse, recommends their own adhesives. Either a PF-50/65, PF-40, or PF- 50. This stuff tends to run about $250 for a 5 gal bucket. Which, given the spread rate, amounts to over $1 per sf just for the adhesive! More than I paid for the floor!
Does anyone know how this stuff compares to the Roberts 1404 that I can pick up at HomeDepot for $50 per 4 gal bucket? Or anything else less expensive?
I really don't care if I void any manufacturer waurantees. I just don't want this stuff coming up later.
Thanks. Steve Maring snipped-for-privacy@maring.org
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