Let's separate photo from video.
Still photo editing with Photoshop requires minimal CPU power. But a certain functions like the quick selection tool would be a lot more intuitive if you have a faster graphic adapter. Any CPU built in the past 5 years is good enough.
For video editing, that depends on the version of software you're running. The later or latest editing like Premiere Pro, or Premiere Element has proxy (ingest) editing which smooths out the real time display a lot. You can do 4K without any real issue if you're running 1024x540 cineform proxy. I would suggest an i7 with quad (2x dual) core capability. Again, a more advance graphic adapter would do better. That's the editing part. When you output, depending on the processor, it could be faster with a more powerful CPU.
I would want to have 8 to 12gb DRAM minimum.
A SSD (240+gb) is nice to load the program and boot up fast. A 1+TB for enough of the storage.
In the US, it is within the US$400 range.