I can't comment on Dayton, but any DIY is going to be a lot cheaper (it if wasn't, why would you bother with the DIY - would make no sense). My PB Ultra is four years old now? My 'amp' went, turned out to just be the fuse, It's running fine. As for sound quality - far better than any B&M sub I've heard at twice the price. Those are good subs too, but too many markups in there. SVS also have a very very flat fq response, most other subs don't. You can get that though with a lot of tweaking and bass traps I'm sure (and though the SVS's are flat it is very dependent on room location, shape, etc of your space).
As for moving air, I have a 2808 sq foot house. My PB ultra is in my bonus room which is 18 x 15 with a 16 foot vaulted ceiling completely open on one side to both the upstairs and downstairs. I feel the air slam me and it shakes the joists in my basement. I already put up with enough grief from my wife about it so getting "twice as much
' power for half the price would be useless as I couldn't use it anyway. Not sure why the BASH amps in these things are faulty but at least SVS is willing to work with the customer to replace it. I can think of another company that went head to head against SVS - ask those guys how their customer service is even before they went under.
And of course, everyone's 'sub' is 'the best' and 'twice as good, twice as loud' as the everybody else's 'insert brand name here' sub. That 's just how it goes here. I feel sorry for you guys that have a sub that is twice as loud, and pushes twice as much air. It may be half the price, but I 'd hate to see your bills that mount up every month for broken window, broken china, broken glass, and anything else that falls out of cupboards and off ledges from all that 'air' moving and all the vibrations happening throughout your home. I doubt in the end it would be 'cheaper'