i got a variable ND filter from amazon for under £10. now, i'm not saying it's gonna be great, but it's cheap and if you're new to NDs (like me) then it might be a better option until you know which strength you're going to use more often.i got this one:
http://www.amazon.co.uk/gp/product/B...ls_o06_s00_i00 which is a 58mm thread. the higher the number (ND10 as opposed to ND9) the darker the filter, so the longer you can keep the shutter open before blowing the highlights. i think. hopefully someone with mroe experience will come along soon lol
