AMD launched the HD 7950 clear back in early 2012 -- over five years ago! At its height, the HD 7950 could earn about $3 per day and cost $330. The R9 280 was the same card, rebranded in March 2014. Cryptocurrency prices had changed so most of the time it earned closer to $$1.50-$2.00 per day, but the card was now available for $250.
The R9 285 was technically a new GPU architecture, released in September 2014, but performance was still essentially the same, and so was the price -- the R9 285 was a lateral move. R9 380 is yet another rebrand, this time of the Tonga architecture used in the R9 285, with a minor bump in GPU clockspeeds. The price also dropped to $200, but mining potential didn't really change.
So what exactly is the earning potential for the R9 380 these days? Here's how my card is doing:
my numbers ended up being slightly different in a few cases -- probably because I only bother with NiceHashMiner these days.
Bottom line is that the R9 380 is still good for about $1.50 to $2.00 per day in gross mining profits via NiceHash, or if you're willing to mine other coins directly (Expanse is good right now) you can earn a bit more, perhaps $2.50. Power for the R9 380 is actually one of the few areas where the card is substantially improved from the old HD 7950 Boost, because the 390 uses between 125W and 150W for mining, or about 75W less than the 7950. That means where the old 7950 might cost $0.50-$0.60 per day, the R9 380 costs more like $0.30 per day.
You can still buy R9 380 cards, though in most cases it's not worth doing -- the RX 570 costs less and performs better. But if you're willing to buy off eBay, you can get the R9 380 for $120 or so. At that price, earning $1.50 per day, you could break even in just 80 days. That's actually pretty awesome, and it's because the mining software is well optimized since it has been around and popular for so long. As an alternative, the R9 380X is a little bit faster and generally costs the same, so it could break even in as little as 70-75 days.