The coupon/code is a bit confusing in that it doesn't reduce the sale price of the thread directly; i.e., the thread is on sale for $1.85 but, as mentioned marknfran, the code gives another 6% off.
I just found a sales receipt for Maxi-Lock from a local shop (where I just bought my serger) and their price is $3.99 per spool. Comparing that to Atlanta Thread, for 8 spools at $1.85 plus discount of 6% and shipping ($6.25), each spool costs $2.52 which is a 47% savings, if my math is correct!
My order was just shipped (ordered last Thurs) which I think is pretty good service.