Hi Madonna,
I'm just catching this thread a little late, but I wanted to offer you another option. I naturally have always had very little hair at the outside edge of my eyebrows and for years it's been my daily routine to fill them in.

If you want to try this, first of all pick a powder eyeshadow that is close to your natural eyebrow colour. Then get a small, angled brush. Apply some powder to the brush and with short strokes try filling in the thin areas. Blend it into the parts of the eyebrow that still have plenty of hair to help keep it natural. Then comb over it with an eyebrow brush to further blend.

This may take some practice to get it down and looking natural, but I get many compliments on my eyebrows (not to sound un-humble!:lol ) and like I say, I've been filling them in for years.

Another idea might be to go to a makeup place (i.e. in a department store) and have them do it for you the first time. This should be free although they might pressure you to buy their products. I'm not sure where you live either, but this is pretty common in North America. That way, you could see how good it can look with a little practice!