CPU: Ryzen 7 2700 ($150)
CPU Cooler: Scythe Fuma 2 ($60)
Motherboard: MSi B450 Tomahawk MAX ($115)
RAM: Crucial Ballistix Sport LT 2x8GB ($60-75; set to 3600MHz and use the memory timings the Ryzen DRAM Calculator spits out. Drop the frequency lower if your chip's memory controller can't handle it)
SSD: Whatever is cheapest of the 1TB Phison E12 + Toshiba BiCS TLC clones (list in the SSD subforum; $100-$120 usually)
GPU: Sapphire RX 5700 Pulse ($320-340)
Case: Phanteks P400A ($70-$78; the P300A is coming out sometime this month if you want something smaller. Basically the same but shorter for a more compact system and slightly less expensive)
PSU: Corsair CX450M ($35-$45 when on sale; check if the 550W or 650W models go on sale as well)
I added on 2 fans you can use as front intake to replace the 2 the P400A comes with (or the one the P300A comes with). You could also get the Arctic P12 5-pack instead and just use 2-3 as front intakes, one as a reduced speed top intake in the top front fan slot (only applies to P400A. Don't bother with a top fan for the P300A), and one as an exhaust (or just not have an exhaust).
You could also get a Ryzen 5 1600 AF (YD1600BBAF
BOX which is $85, don't get the AE one) which is effectively a Ryzen 5 2600.
There's also supposedly the EVGA RTX 2060 KO coming out which looks to be quite good for the money.
You could change out the Fuma 2 for a Mugen 5 to save around $10 but prices for the Mugen 5 seem to be whack right now. It'll probably go back to normal soon.