Hi,
Meyer Sound X-10 are $US 30,000 the pair last I know, thus directly competetive with the ATC SCM 150 ASL on price, even though their performance is well above and beyond the biggest ATC's on all counts (ATC SCM 300ASL is rated at 121db/1m max, Meyer Sound X-10 manages 136db/1m no sweat!).
The ME Geithain RL-901K which is in terms of Max SPL comparable to the ATC SCM 150 ASL retails in the at around £ 7,000 the pair here: http://www.firstsense.co.uk/meGeithain.htm.
The K+H O500C are competetive with the MEG IIRC, I have no current UK/US price at hand, go an look.
Ciao T