If you're going to be paying $5 a sound, why not book half an hour or so in a level D sim - I know they're prohibitively expensive to run but maybe you could come to an agreement with the organisation to do what you need to do, you won't need the motion or an instructor, just a techie to supervise perhaps. Here in the UK you can purchase time in level D sims I'm assuming you can in the US too?
I reckon you could probably get everything you needed in half an hour or so if you planned it all out....? Plus you'd get exactly what you want and how you want it.
If there is anything you MUST have the actual aircraft airborne for (slipstream sounds for example, seem a bit weak in the sims from what I've heard but I may be wrong!) then you can revert to your original idea...?
Trying to weigh up cost effectiveness with results achieved...