I'm looking for 2 sets of speakers and a four channel amp.
I want to keep it under $400
I was thinking of buying two sets of Polk Audio db651 ($60 a pair + ship U.S)
and a Rockford Fosgate P450.4 ($200 either ebay or a local kijiji)

Any suggestions on better gear?
anyone have this gear?
Thanks!

 

that's an extremely tight budget for anything decent. I'd suggest getting some good speakers and runing them off the head unit for now, and saving some extra coin for a good amp down the road.

 

Ok, I feel like being impatient so let's make the budget $600
What changes now?
Is the amp good enough? just need better speakers?

 

better speakers,Go to some local shops and preview what they have. get a better idea instead of asking for part numbers from forums members who don't know specifically what you're trying to achieve with your sound system.

 

Go to East Hamilton Radio. Listen to all the different speakers. Bring your own music too.
That's a good place to start. Find what sounds good to you. Get some information from the sales people. Then come back here with what you've come up with.
I'm sure there's a few audio shops in Hamilton you could check out. Once you find a product you like, then you can try and find the place that'll sell them for the least amount of money.