So recently I bought a Garmin eTrex 30x and was wondering what maps you use with these units.

I've found http://garmin.openstreetmap.nl, are these the best OSM maps available and which of the map types do you find best?

The Garmin OS maps are outrageously expensive. I've seen references to cheap OS maps on iOffer but I can't find these, is there anywhere affordable to buy OS maps for Garmin?

The chap on ioffer seems to have vanished. There are also good maps on Talkytoaster. I used the Osm you linked to in Normandy over the summer. The lack of buildings and contours led to a few surprises.