Gallo TR3 is 799$ new, used ones don’t show up on here(a good thing). One sub is all that’s needed to play the odd organ piece and relieve mains from
burdens below say 80Hz which brings more clarity which is always needed .
I’ve heard Vandy subs but IMO Gallo beats them.
If your Oppo is less than a 105 a Cambridge CXC transport(449$) might do more for system than sub .
Might do more if it is a 105 .
Some say two subs evens out bass in room. I've found one is enough IF you get the placement right .