Personally I think you got an excellent deal for this domain.
Details are: 25,600,000 Google results, 39,100,000 Yahoo, Overture/mo 145877 Wordtracker/day 7846
Now the EstiBot.com Valuation : USD 12,000 seems a tad high to me but I would definately put it in the $xxxx range and to an end user...who knows?