My apologies if this has already been covered (I searched but didn't find anything) but I wanted to communicate a way of obtaining reasonable-quality diamond files at a very low price.
Most diamond files consist of an adhesive-backed strip of diamond abrasive tape attached to a plastic or metal carrier. This is true of Moonflex, SVST, Swix, Tools4Boards and Icecut at a minimum. The only major exception that I'm aware of is DMT, which embeds their diamonds into metal strip and bonds that to a plastic carrier. The SVST files in particular use 3M DiamondFlex PSA-backed tape (http://www.svst.com/ItemForm.aspx?item=4WCDF120&Category=a4fd2444-8d92-4846-8dca-09e8e4d322d3).
My personal workflow for some time has been to use Moonflex stones in a 5-grit progression (100-200-400-600-1500) for my racing skis, and the SVST stones in a 4-grit progression (120-220-400-600) for everything else. I only use the 100/120 stones if I need to take down case-hardened edge sections or if I'm using the diamonds to actually sharpen the edge (I usually sharpen by filing and then use the diamonds to polish out striations/burrs).
I recently was in the market for replacement diamond tape for my SVST files, and on a lark I did a fairly broad search for retailers selling the 3M-branded DiamondFlex tape as opposed to the SVST-branded tape. The 3M tape turns out to be widely used for jewelry-making and is available for remarkably low prices. For example Rio Grande sells a kit containing 7" long strips of all 4 grits for $17-19 (depending on qty) or individual grits for $6-7 each. FDJ Tool sells individual strips for $5-6. See:
The 3M-branded strips have slightly different grit ratings than the SVST ones (120-280-400-800 vs. 120-220-400-600) but they actually appear to be identical even under microscopic examination. I've been using 3M strips cut down to 4" as replacement strips for SVST files (which I bought from SlideWright - highly recommended) and also to make 7" "cheapo files" by laminating them to aluminum bar stock. I haven't seen any substantive difference in quality of results vs the SVST-banded tape. The jury is still out on longevity, though the 3M strips have already lasted long enough to be clearly more cost-effective than the SVST tape.
I still use Moonflex on my racing skis, but I've now completely switched over to 3M tape for everything else.
I've also started experimenting with the 3M MicroFinish strips (aluminum oxide on PSA-backed polyester base) for final polishing.
They seem to work quite well, and are priced low enough ($0.60 per 7" strip or so) to be treated as consumables. This is a significant time saver as it eliminates the need to clean metal filings out of polishing stones and/or lap them on drywall screens to remove scoring. The polyester backing of the strips also seems to be more resistant to scoring than some of the softer ceramic stones. I'm continuing to use the SVST T2 and Al-oxide stones on my race skis for the time being, though.