Purely from SE traffic? This could be costly as it would take time to search and optimize the site for the keywords that you wanted. I have a few sites that have 100+ uniques a day easy from SE's alone and it takes some hard work especially for a competitive keyword.

If you were just referring to 100 uniques a day overall then it wouldnt be as costly. Were you looking to higher a consultant on advising you how to get your site to the 100 unique milestone? This is what I think youre asking for. From past experience I have charged $250/$250 budget for a month. I've done this with 3 different clients after designing their sites. What I do is basically optimize the site and purchase targetted advertising for my clients site, for the trouble I receive $250, the second $250 is my advertising budget. I've been pretty successful in boosting traffic within the month so that sites would be getting steady traffic from SE's and word of mouth after the month is over.