Hi - I've been using a natural product "Citronella Insect Repellent, spray lotion", put out by Druide ,
It is a certified organic product, available for $8.29 (Canadian) in 130 ml size.
The label says its 10% essential oil of citronella; and 5% citronella terpene.
It really smells like citronella, and is very effective against mosquitoes (tested so far in Quebec, Ontario, Maine, Michigan, Minnesota).
I like it, but it does smell quite strongly.
For the English version of Druide's website, go to: http://www.druide.ca/Default.aspx?Langue=En