How much would it cost to do this?

[Session25 10+ year member]

all they did was make a pretty faceplate for a sub box. yah it looks good but u can definately do it yourself.

yeah i guess i could do it myself

 

[PV Audio 5,000+ posts]

Simple false wall and false floor setup. You could do it very easily, but they'll charge your ass ~ 7-8 bills for it. Trust me, I've seen people pay upwards of 1k for iffy false wall installs from shops.