Its actually the most that I have ever paid for a Bitcoin miner.
Well thats 2.5months ROI on free electricity. Compared to GPUs right now its not really good but still. On free electricity this is not a bad deal at all if you are on free electricity. If you pay, then not sure.
Yes but what changes this time is the halving. Right now an S3 makes more money then a S5 will after the halving with free power, and right now people are pretty much giving S3's away and nobody is buying them. Which means that an S5 won't have much value after the halving.
So if you buy today for around $150, it will take 3-4 months to pay off. After its paid off, it might be worth like $50 and that will be your profit. Doesn't sound like much does it. An A6 or S7 which has a slightly longer ROI period will make more per month and will hold a fairly large value as compared to an S5.
Its for the same reason why you couldn't sell those tube miners because they hold very little value because they consume more energy then they make BTC. But your A6/S7 will probably sell very well in the next 6 months or so.