You can attract commends and readers in many ways.
John Chow often uses contests – even though he actually always gets a huge amount of comments to his posts. This is probably due to his very special personality, which you most likely either hate or love.
If you only have two readers, it will not pay off – unless you can attract traffic through other means. Are there any sites you can tell about your free contest? Then go ahead and do it – it will give you a lot of traffic, if your prize is exiting enough.