I put on a couple NBA games and finished up 4-channels of Helios mic pres last night. Still need to get the front panels made, but at least they all seem to work when I checked them out at home. They're based on two '2128' amp cards in a row with a gain in the first stage, a trim control in the middle, and a discrete buffer on the output (helios apparently never used balanced outputs on anything, so there's only a transformer on the input).
As far as DIY pres go, these are pretty affordable - not a lot of parts, only one transformer, pots instead of stepped gain switches. Probably about $150CAD in materials per channel (plus whatever the panels end up costing I guess...).