It is suppose to be for first time buyers, I bought something else from buy.com and tried to do it the way that first timers do it, but I still did not get the 10 bucks off, like I was suppose to...If you have a gmail account, you may not be eligible, but that is speculation...either way this is a killer deal on a TDS meter, I am going to order this, just so I have an extra one laying around.
As for someone thinking this is a scam...it is not, buy.com is a huge company that was started to rival amazon...so they are legit and not stealing your CC#, plus google is on it and they are also the #2 most visited website, so they are not running a scam either...