I love a nice gray color on my nails and I think I have too few in my stash, a very welcome member of the "gray's" are Kleancolor - Concrete Gray. It's a creme and has a dark gray color which is purple leaning in color which make it look quite purple in some lights. It takes 2 coats to cover and I really like it. :)
Bought from Ebay. Total per bottle is like 14-19 SEK or like 1,5-2 euro.