Yep, that is legit! You can check Whois.sc about a domain if you even hold question about it also...
Getting an offer that way from NSI, is Many Times likely to be an End User! It cost $19.95 PLUS 5% (i think it's 5%, could be 10%) of the accepted offer price for the buyer to use it!
FreeQuotes.com sold from a NSI Certified Offer for over $200K :kickass: