Micro commerce feature I need to add a new feature to my site that allows users to buy a services.

We have 1 service now to be sold, and may extend to have 3 in the future with no attributes nor shipping, just a sales price.
 What should we use to implement this? 

Commerce, ubercart or none of them?
you can sale services in both Commerce and Ubercart. But if you look for simplicity I should tell you Commerce is simple and light enough.

At this time I can't remember any other solution on D7 except writing custom module. which I don't recommend.