I had installed a KDK ventilation fan model 15WHPA at my master bathroom by last year, which charged me $350.00 all-in, me and my wife are very happy to their service and installation job, it looks very professional, althought the price seems like a bit higher, but it looks really nice to my toilet and don't spoilt to my deco.
Before we commited to the model 15WHPA, we did checked with KDK people why other people is only $100-200 all-in, lastly I found out that is different model (15WUD 6'', the fan cost is cheap, of course total price is low), for 15WUD is more to commercial building, old model with round shape outline and not safety to install at residential, we don't want to make our house like commercial building, so we decided to go for 15WHPA 9'', new and square shape with louver cover which is more safety when it spinning.
They also told me this is high pressure type, we don't smell the 'good smell' in the toilet anymore, now we are planning to install another one at the common toilet.
In my opinion, is 'yi fen qian, yi fen huo' loh.