In 2006 or 2007 the 4B-SST was around 3300(depending on the dealer)up to 3600
The 7B-SST was exactly the same price as the 4B-SST and has the SAME amount of power(combined) as the 7B-SST monoblock. Jezzuz have had the 7 for that long(10yrs.) and nada problemo.
Course she does just centre channel duty so I'm sure she's not even broke in yet

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I bet my 7B-SST2 doing surrounds duty will never be really broke in LOL.