Pretty cheap here on Amazon... else aliexpress?
It's not really complicated. You need 2 video outputs on your motherboard and match them up to the ones on your monitors, so you need 2 cables all the way from the PC to the monitor. Most common ones these days are Display Port (D.Port) and HDMI. It does not matter if you plug one monitor with D.Port and the other with HDMI, so long as both are plugged into their own ports on the Graphics card (it will in the vast majority of cases not work if you plug one into the GPU and the other to the motherboard).
You don't necessarily need an adapter, there are cables with different connectors on each end, just be careful to buy the correct one as they are one directional. For example, if it says Display Port to HDMI then that means display port goes into the PC and HDMI to the monitor, not the other way around.
Here is an example of a cable: https://www.amazon.com/DisplayPort-Gold-Plated-Avacon-Display-Adapter/dp/B01FX3K7T2/ref=sr_1_6?keywords=displayport+to+hdmi+cable&qid=1686519375&sr=8-6
Here is an example of an adapter: https://www.amazon.com/DisplayPort-Adapter-Converter-Gold-Plated-Compatible/dp/B017Q8ZVWK/ref=sr_1_4?keywords=hdmi+to+displayport&qid=1686519632&sr=8-4
Again, as I said, be mindful of how it's listed. In both of my given example links the HDMI port must be on the PC side, while the display port must be on the monitor side. If you need the opposite then it would be called HDMI to Display Port like this https://gembird.com/item.aspx?id=7873 though if you have enough matching ports then you do not need adapters at all
Chromecast plugs into an HDMI, but that shouldn't be an issue. I use this cable on my home rig and at my company all the time with no issues: https://www.amazon.com/AmazonBasics-DisplayPort-HDMI-Cable-Feet/dp/B015OW3M1W/
You'd obviously need the HDMI end to be female, but there are definitely adapters. Something like this would probably be fine: https://www.amazon.com/DisplayPort-Adapter-Converter-Gold-Plated-Compatible/dp/B017Q8ZVWK/
Base level Chromecast is $35, so you'd be under $45 for the whole set up. I doubt you'll find anything else that is significantly cheaper out there.