That's not too bad I guess.
As a matter of fact that is about what I paid for mine back in 2017. Thor was my favorite character when I was a kid, and I stumbled upon the Hot Toys figure online somehow. I had no 1/6 scale figures at that time and it was the first I had ever heard of Hot Toys. So I bought the figure from a retail vendor for about $270. If I had more experience I could have shopped around a bit and found him for less but I didn't mind paying that for him at all at that time. I still have ZERO regrets about that purchase!
So, I don't think $300 is an unreasonable price for this figure, of course I am biased