TBH I was just looking at your chosen parts and going by known "sale" prices. I look at newegg's sales flyers EVERY day. All in all, I don't disagree with any of your choices per-se, just that they're not particularly great prices at this moment. Watch for sales, and if anything, go for it on the week of Black Friday.
Let's see how close I was:
i5-8600K - Good choice, Intel is having supply problems so prices have gone up. They've been as low as $235
AIO - If that's what you want, fine. This was the only part I actually changed to a tower cooler for $40
instead of $90, but a 240mm AIO would cool a bit better if you're OCing HARD. Also the Corsair H100i is $90 after MIR also.
Regardless, I've seen 240mm AIOs on sale for ~$60-$70 recently
Mobo - $185 is a LOT for a mobo. Might want to evaluate what you actually need in a mobo. Would an mITX mobo suit your needs for around $120-$150?
mATX seems to be getting abandoned by mobo makers since case manufacturers couldn't seem to make mATX cases that were any smaller than ATX ones. That's a shame.
RAM - 16GB runs around $120-$140 nowadays.
Of course if you want RGB you'll have to pay extra. Even RGB 3200MT/s has been around $140-$150 in recent history.
SSD - MX500 is a fine choice, and that $90 is an average price. However, you can get almost the same $/GB with a XPG SX8200 NVMe drive for $110
and that's before Rakuten's frequent 15% off everything sitewide sales.
GPU - GTX1060's are typically around $250-$260
Case- Not a bad amount of money to spend. I don't follow this particular case, so ok. What do you think about the Phateks Enthoo Evolv for $60?
PSU - Good choice. Price is good, they usually go for $50-$60 on sale. Here's another one to watch for $50-$60.
Subtotal = $1,000 - $1,100
Main: i5-3570K, ASRock Z77 Pro4-M, MSI RX480 8G, 500GB Crucial BX100, 2 TB Samsung EcoGreen F4, 16GB 1600MHz G.Skill @1.25V, EVGA 550-G2, Silverstone PS07B
HTPC: A8-5600K, MSI FM2-A75IA-E53, 4TB Seagate SSHD, 8GB 1866MHz G.Skill, Crosley D-25 Case Mod