Your choices look good - the larger Paradigm in walls can rock. The standard in walls are necessarily very shallow speakers and not that good (I have B&W's everywhere and they are kinda ok for what they do). If you want to buy some used some big box audiophile speakers then you will need to build cabinetry around them (picture frame around baffle and smooth front surface). This can work well if you use mdf (not lighweight particle board or wood) but is much more expensive than a simple drywall...on the other had cabinet space is useful for media storage and you can use proper audiophile speakers of your choice.
I really don't want to spend $500/speaker - I will if I "have to."
It will be tough to get good quality for a main system if this includes in walls and installation. Have you considered a wall mount TV and wall mount speakers on extendable brackets (again you could install heavy audiophile monitor speakers if you use omnimount brackets into wood studs with lag bolts)