get the SVST file guide. the stainless steel one is really nice but twice the price of the alloy ones. I have happily used the alloy ones for years, just get it. For files the bets and longest lasting I have found is the Swix 8inch second cut. For Diamonds, as others have stated, moon flex is hard to beat.
Go to Artech ski and get the the SVST 3 degree guide, swix file and moon flex red and yellow (200 and 400) and you are set and with their current sale you should get the lot for about $120
Out of most of those until August.