CPU AND MOBO: If you don't mind buying used, you can get like a cheap b350 and even a cheap x370, pair with a ryzen 3000(if you game a lot) or even used 1000 or 2000 series and you good to go.
CPU cooler: used stock cooler you buy new CPU or grab a SNOWMAN cooler on aliexpress(it's fairly cheap and it's a half decent for OCing).
Ram: Try to get 3200Mhz 2x8Gb kit, and you can overclock it to 3600(maybe and if you go ryzen 3000).
GPU: Because you don't need "RTXon" so used Pascal (like a 1080 or 1070ti or even 1080ti) is a good option but you can also go new and grab a GTX 1660 super(the performance is lower).
PSU: Buy a new PSU!!!, we have a tier list on our forum, feel free to take a look.
Case: just buy a $70 case that have good airflow and a pack of 3 fans(if you case not included).
P/s: Don't go RGB if you can't afford.