Also will buying $100 speakers for surrounds, center and sub a waste of money?
Frankly yes. It kind of defeats the effort to get trueHD surround sound, which won't be all that different from regular Dolby Digital or DTS. I think you will be disappointed with it. FWIW I'd stick with your AVR230 and just feed it digital out of the BD player and get matching used 718's and a sub to make a 4.1 system. Alternatively keep saving and then upgrade your mains and move the 718's to surround role. Use Phantom for center channel and keep the speakers slightly closer together than you might do normally - and you'll be fine for one or two listeners in the sweetspot. (IMHO skimping on speakers in a surround system will leave you dissappointed and you'll want to upgrade again only too soon).