Deciding if PPC would be profitable?

Hi Guys
I hope I’m using the correct terminology here, bear with me please if I’m not.
I have a small mini site (1 page). The site has generated around $60 in adsense in Feb so far (22days) and sold around ten books using my amazon affiliate.
How would I go about deciding whether or not it would be profitable starting my own PPC advertising for the site to increase visitor numbers and generate more income from it?
Any help/guidance/links to info would be greatly appreciated.
Thanks
Phil
Here’s some stats from adsense for February (22days)
page imp. 2070
clicks 124
page ctr 5.99%
page ecpm $29.39
earnings $60.84

See original post by philb