When buying system whats the order i should buy in if i cant buy all at once

[noddin0ff]

I'd get the mains and then listen to them for a while. You can try phantom center with only mains as well. If you feel that the dialog is convincingly coming from the center when you listen (as Kexo said, seating position is critical here) then you can pass on the center for a while.

I added the sub last. And since I don't usually listen at really loud levels I don't feel it made a huge difference to my experience and I am happy it was added last. It certainly fills out some of the more bass heavy music, but for most of my collection I can live with out the sub. Placement for smaller speakers can help reinforce the low frequencies and is worth playing around with.

If you like the action flicks, with lots of flying gismos or arrows/bullets whizzing by. Then rears are needed. I say you can get thrills with smaller less expensive rears if you need. If you also want pounding explosions you'll need the sub. If, instead, you listen to a lot of dialog oriented art/romance flicks, then you'll want the center so you can hear what they're saying.

There's no right. But going slow and thinking about what you want in increments can keep you from making too many wrongs.

[kexodusc]

If you like the action flicks, with lots of flying gismos or arrows/bullets whizzing by. Then rears are needed. I say you can get thrills with smaller less expensive rears if you need.

For Studio 20's, something like Paradigm Atoms used as surrounds would do 80% of the job at a fraction of the price until you saved up enough money. Atoms go for $100-$150 used, you'd get most of that back selling them later on.

Truth be told you could do the same with a center channel as well - it's not optimal, but I've done it before and much preferred the mis-matched center to Phantom Mode.
Paradigm (and companies in general) tend to build "signature sounds" into all their models - so at least partially matching is possible.

FWIW I wouldn't go cheap on the sub. That's one piece that will wear its shortcomings on its sleeve. Get a decent (not necessarily expensive or large) sub when you decide to buy one.