I like them, they look good, and seem like a lot of work was put in.
I'd say about 200-350g, based on complexity.
Like the first sample would be in the 300 range while like the third sample, in the 200 range.
I think that most signature shops on Mene sell art for around 20 gold.
These quotes that you're getting sound a bit high.
Just poke around the pixel art/other section for some more accurate ideas.