might be a good idea to mine bitcoin or to buy some GPUs (whose price doesn't change so much during month) and start mining other cryptocurrencies ? that was my dillemma. Is there any other good producer except Antminer ?
https://canaan.io/shop/Canaan Creative.
Their newest miner is AvalonMiner 721.
You need AvalonMiner 721, controller (Raspberry Pi) and a power supply.
Unless they've started accepting non-bank transfer methods of buying their miners, it's not really easy to purchase their miners. Plus, the efficiency of the A721 is just around that of an underclocked S7. I know some people like me support Avalon and other miner manufacturers, but it's not too ideal to buy one at this moment unless you want a nice starter rig and have nearly free electricity.