bunch of crap. you can get so many subs that are at or below that price range just as loud. dont let your companies be limited for one opinion. however, they are a fair sub with good power handling and can make some good spl. they sound ok in ported boxes, not the best though. there are definitely way more options. just to name one: memphis M3s. those can take a ton of abuse. cruch groudpounders, very cheap and loud.
anyway, what makes a good sub is definitely build quality. a basket that is nice and study for what that sub needs to do. a strong coild former and one that doesnt build up too much heat. the cone no matter for sq or spl should be nice and firm so it cant flex side to side and come off as making the coil move in a crooked manner. tinsel leads are usually best when integrated into the spider. this way they cant slap the back of the cone during excursion. surround, rubber is definitely a good surround. as far as performance though, its fairly similar to foam. however for huge excursion subs like the edav2, they prob need to use a rubber. its better for uv protection too, something to think about in a daily driver to an extent. after all this comes how well it can really perform and it definitely helps to hear from a credible source about a subs performance. and not just a biased one like above. i know so many people who have a lot less than 10k and can hit 150dB all day on a termlab without some type-rs.
o yeah didnt mention. it doesnt stop there, though. its really ALL in the box. the sub is merlely a tool and then you build around it. the box and what you do inside of it are what can give anyone a loud score with 2k.