We use plain old PAR38 lamps pointing up into our currently unlined ceiling space...one in each corner...lights our 5x8 metre very effectively without blinding occupants. One is a CFL globe and it gives much better quality light (warm white) than the other three...
Cheap effective solution thus far...
If you like you could go to the smaller PAR20(?) lights. But don't be scared of CFL...or the better LED versions of the PAR38 either.
Failing that...this mob GU10-GZ10 - Products - Gentech Lighting - Importer, manufacturer and wholesaler can supply most of these fittings and it seems many of their other spots with extension rods. Hang them from the ceiling but point them into the rafters - same principle. Can't suggest they'll be cheap but!