You're probably not getting a reply because (1), we're scouring the web for Black Friday bargains and (2), there's so much stuff available to do what you want, we don't know where to start.
(A) Tons of free reverbs, etc., available a VSTplanet.
(B) If you simply must pay, try this one:
Dreamscape Reverb Space Generator Plugin
(C) There are scads of great vendors with demo/trial versions of their reverbs, just waiting for your auditions.
(D) Since you memtion CPU usage, you may want to investigate the "trick" of setting up your reverb on a dedicated track and feeding your source track(s) through it as aux I/O (one reverb, different wet levels for individual tracks).
(E) Personal preference: record dry, add the effect later. Simultaneously capturing the source and the ambience is not a simple task and removing reverb from a recording is a lot more expensive and time-consuming than adding it to a dry track. But, whatever works for you.
Paj
8^)
Paj
