Ignore the dollar amounts on appraisals, all you should be looking at really are the searches, the competing pages in those ranking pages and the cost per click of advertising if you are going the adsense route.
I have looked at the existing .com and .net already and have to say they are pretty useless, they are nothing but parking pages...
If you can do something and get to the top of the heap you will have a very nice little earner but it certainly will not be easy, there are over 900,000 competing pages for "Advertising Company" and it will be an uphill battle.
Right now it is worthless, get it ranking and who knows?