Skar rp2000.1D refurbished is about the best bang for your buck at $159.99
But for more quality:
Sundown
Crescendo
DC
Korean versions of budget brands like soundqubed Q series Skar SK series, Wolfram audio, Alphard.
For wiring kits I like Sky High and Knukoncepts. Generally you're better off going with OFC and welding wire is more cost effective. However sky high CCA 1/0 is actually 2/0 and at $40 shipped for 20ft is a really cost effective wire for ~2,000 watts.
man, the world of amplifiers has changed so much since the Korean onslaught of offerings from zenon and s&i, its hard to really say what amp brands arent any good when youre looking at stuff. There are many amp brands to avoid like the plague, but youre gonna get a ton of responses saying that x brand is the best and likewise with y brand. That being said, there are two prophets of the pulpit that we all thank wholeheartedly for their contributions to our hobby, that you should probably spend some time watching their videos as they literally bench test amps and post videos of their findings for all to see. BigDWiz and Bigblank69 are the two dudes i speak of.
tl/dr what are you looking to amplify and whats your budget? Subs? fronts/rears? active x-over? we will plague you with questions before providing an answer for amps waaaaaay before we answer about headunits like in your other post. Let us know what your goals are and we WILL help. Thats what we do