In order:
- $315 - Sapphire Nitro
- $358 - Asus Strix 380X - looking at this one.
- $485 - Sapphire Nitro
- $479 - Windforce OC
Polaris will be the same if not more (likely more). I'm looking at the 380X, it seems to be a modern 7970 equivalent more or less. Seeing as AMD drivers mature as opposed to strangling older products I doubt waiting would make much difference. At least pricewise.
Those prices are
way too high for what is essentially a slightly faster 2012 HD7950 V2 (Ya I know Tonga XT is faster stock, but overall it's not any faster than
November 2012 $300 USD HD7950 overclocked to 1150mhz. If I had to choose a 380X, I'd go with Sapphire Nitro since it's the cheapest.
Why not go for the standard R9 380 4GB and save $? If you are happy with 40 fps then I doubt 380X is even worth getting.
R9 380 vs. R9 380X in 14 games
https://www.youtube.com/watch?v=Od1lfnJW7ug
In many games the 380X is barely faster than a standard 380 and slower than HD7970Ghz.
http://www.guru3d.com/articles_pages/amd_radeon_r9_380x_4gb_review,9.html
IMO, the 380X sits in no man's land based on the prices you have outlined. Might as well step-up to the R9 390 or go down to a 380 4GB if you don't want to wait for Polaris 10 or wait for price drops on the 390.
Even if 380X is cheaper than 970/390/1070, its price/performance may still be way worse. Have you calculated that?