I’m looking for an rpk. Not too picky on the model. I’m jus wanting a heavy barrel, thick receiver, that can handle cycling a lot of rounds (wanting to use drums). I haven’t had much luck looking online for rpks for sale. Where would be a good place to start?

Gunbroker or go to Apex, buy a kit and build or have it built.

Came here to post this.  A member here built mine for me, not sure if he’s still around.  I got the Romanian parts kit from apex and a nodak ( ? ) reciever.  I like it a lot.  Unfortunately for me now there are better barrel choices, nitrided and chrome lined are available, mine is not.. Maybe I’ll get it replaced someday...

I just picked up a James River M72b1.   Looks nice.  have not got to shoot it yet.   I paid 799 plus shipping for it.
Normal price is 849 but they had it on sale which if I had picked one up last year they were 749.  
Drum locks up tight.

Go to knob creek. There should be some there for sale this weekend.

What’s the site to these?

classicarms.com

I would recommend aes10b or other stamped sheet metal receiver rpk. You will have more options on accessories. Just keep an eye on gunbroker. That is where i got one but took a year to get a decent deal. Im poor though. I had the drums for it a year. That was the deciding factor drums were on sale and i spent a couple hundred bucks on them.  You cannot melt it down in semi auto. They are supposed to withstand 80rpm without issues. Finger will get tired before the gun.

Get one with the bipod.

Wished i had got the AES10b when they were under 600 bucks