keywords (wordtracker + overture) questions

how many searches is considered a "lot"? how many is considered too few to optimize for?

I've only done a non-profit site's SEO before- and their primary phrase gets 14,000 searches a day according to overture, and 15,000 a day according to wordtracker.

I'm thinking about doing my first commercial site, and the keyphrase we were planning on targetting is quite small- wordtracker is reporting 46 a day, and overture is reporting 4 a day (that can't be right..)

how many searches-per-day is "too few" to optimize for in google?

assuming you can get to the #1 spot in google, how many hits do you get a day for that term compared to the wordtracker or overture searches-per-day?