Hi chlorophyll
If budgets are tight, Pre Owned stuff would be the answer, based on which location you are, check OLX/Quikr/HifiAds and For Sale by Owner Section...sometimes you get good deals on excellent products....
If you want new stuff, purchase the required model / brand of AVR first and a pair of speakers so you can use the same in stereo mode....as and when you have budget availability, get the sub, surrounds and center speaker...this is what some members have done......
if you are purchasing from ProFx...make sure you demand the 10-20% discount....