Look at the ATC active monitors - I think the SCM-20's. Not sure if they are in the same price range as I don't know the NHT's.
You'll be hard pressed to beat the pricing on the NHT M00s, though they aren't typically considered a surround speaker. A more costly speaker, but less than ATCs typically, are from M&K.
You might scan their direct sales web site.
Hmm, any idea where one could get ATC actives here in the U.S.? I'm in the greater Philadelphia area.
They do show up occasionally on the used market here. A quick web search located this CT ATC Dealer. They are definitely on the more expensive side of active monitors. I heard a pair of 20's in a very nice system and was very impressed by what I heard. This seems to be reflected in the few real-world comments I've read here in the forums.
Don't what you expect or want from surround and center channels. I know I've been disappointed with the quality or astounded by the price. I've found that spending thousands for surrounds is unnecessary, the demand on them doesn't justify it, but spending only a few hundred gets you speakers tinny and inadequate. I was just naïve enough to have tried building my own active center and surrounds. After many weeks of research and much trial and error I've put together something that does the job for me. They cost about $250 each in materials and about 12 hours of time total for a center and a pair of surrounds. Very easy to buildvery simple design. They do an admirable job on center channel dialog and deliver everything needed in the surround channels for movies or MC music. If you're interested, email me.