Used Antminer S9s currently range from $150-178 in the US if purchased in bulk.
IN 2018 Bitmain offered the Antminer 29 as the best bitcoin mining ASIC miner. For over a year it was the fastest and most profitable miner on the market. As 2019 ushered in other models like the S17 and others the hash rates are almost obsolete on the Antminer S9’s. Large mining farms are selling their used ASIC miners across the globe and the market in the US is still on fire even in late August of 2019. Source
Avalon miners which is a sister of China mining firm Canaan Creative, was one of the 1st companies to manufacture Bitcoin ASIC chips. Source
In 2018 BTC.com hosted the worlds largest Bitcoin mining pool on Earth, with a hash rate distribution of 19.2 percent. In 2019 that figure jumped .8% to over 20%. Source F2 Pool is the second largest in ’19 with a 13.1% share of the hash rate.
Ethereum cannot function on the Sha-256 algorithm for ETH mining. Source the 1st Ethereum ASIC miners were on the market in late 2017 as the Bitmain Antminer G2 and the Innosilicon A10 ETH Master.
Ethereum miners currently uses a 850w power supply that generates substantial 485 MH/s
Bitcoin adjusts the difficulty for mining every 2,016 blocks (about 14 days),