Products & brands that last long will not be made in China...so you're either blowing your whole budget on an amp or you're looking to go used to save some $$$.
Have you ever had a system before? I ask b/c you didn't really state your goals other than sounding "nice". If you're just looking for loud & clean; $8-900 will go very far to getting you a nice system...just gotta know what you're looking for and that's the hard part.
Figure $200 for front 5.25" components, $100 for rear speakers, $300 for a multichannel amp, $150 for a sub, and $100 for misc wiring & an enclosure. I don't know if the person still has them, but someone here was selling a set of old Eclipse 5.25" components for $100 shipped. Those things sound awesome and are a steal at that price. For amps, someone is selling an Arc Audio 3ch at
DIYMA for $275 & another has a JL XD 3ch for $260...snag one of those. Why 3ch? Why not? Rear speakers? Who cares...if your factory speakers are not blown those will work fine and if you PM me I can tell you a little trick to get a surround-sound effect from them while running them off your Pioneer HU.
So, we're at $375 right now.
Subwoofer-wise, I prefer lighter coned woofers that don't need a whole lotta power to get moving. 300w going to a lighter more efficient subwoofer can be louder than 1000w powering some monstrosity. Subs that fit the bill for cheap would be Image Dynamics ID line. They sound every bit as good as the IDQv3's, they just cost less. If you want to go REALLY cheap, and this is the avenue I took for my system, look for old school JL subs. I'm talking the original W6's & W3's. Those go for
OK, now we're at $500ish for front components, amp, and subwoofer leaving you another $400 or so for a box & wiring.
A
Parts Express pre-fab sealed 12" box is fine once you make sure you seal off the terminal cup. I think those things are like $35. Pick up a grill to cover the woofer for a few bucks more.
Amazon has some good deals on Monster Cable RCAs...we're talking $20 for BNIB higher end 2ch 6m signal cables. While you're at
Amazon, get some decent 16ga speaker wire too. Stay away from that fancy twisted stuff; it's snake oil and you'll have a helluva time trying to stuff that crap through a door boot/Molex. Plain Jane OFC 16ga speaker wire is what you should look for. You can find a black 50' Monster Cable speaker wire spool for $17. BNIB Monster & Streetwires power wire kits come up for
Past that, I don't think you'll need much else and you'll be well within your budget.