What I mean by this is, if I do a keyword search and say I find that the topic I am targeting for only gets 50 hits a day, would you setup a website to drive traffic into your site using adwords? What would be your minimum amount of searches per day you would "set up shop" for? I am obviously new to affiliate marketing, adwords, and SEO but I do know that you can direct traffic by choosing a combination of different adwords to direct traffic to your site. But if your topic is very specialized and is not related to many other topics, what is your min number? Hope what I've written makes sense.
It really depends on how targeted your keywords are If they are at the end of the buying cycle, for example: buy widgets online then 50 would be enough for me If they are too broad as in widgets then I would'nt waste my time