Hosco now have much more affordable sets of nut files that I believe are fairly new out on the market. A set of 6 files that come with a magnetic holder for making holding the files at the correct angle easier.
Different sets availble, for electrics there are sets for 9s and 10s (though the 10s will happily do for 9s). Also an acoustic set (13s) classical guitar and bass guitar. Here's the one for 10s:
So cheaper still than the 3 x double edged file sets, which will leave a wider v-shaped notch, and less than 1/2 the price of the 10 or 11 piece sets.
At last, a decent set of nut files at a reasonable cost. Still expensive for a one-off build, but it does enable you to set your nut slots up to perfection. There are very few guitars that couldn't benefit form a bit of work on their nut slot heights.