All I can say is, that I know two guys with a quite successful blog (in terms of traffic), that made about 4000$ in their first year through amazon only. though not much in a grand scale, you have to know, that amazon only pays about 5%.

if (and only if) you can build a fairly successful niche-site, than you might think about affiliate-marketing. but don't underestimate the work, building that site. (and the audience)