Do not buy a 1000 series unless the price drops to a maximum of 40% of the MSRP, and do not buy a used card. Remember, a card used for mining will not last long. In order to keep costs down without giving up on stability, they do not take into account thermal considerations for passives surrounding the GPU and VRMs. This is why nvidia warns against using gaming cards for things like machine learning and other scientific purposes, as they are not designed around 24/7 heavy workloads.
Buying a used card will mean that you risk getting something that after a few months to a year+ of use, you will start to experience issues such as the card randomly having the screen become distorted/ checkerboard pattern distortions, or other issues.
Personally, I feel that the 1000 series is a lost cause, and any gamer buying one now will be sending the wrong message to the industry, as by purchasing any of them, you tell them that new generations of GPU can now have 2 lives, each running above or at MSRP, by simply limiting supply and targeting 1 market, then bring it back down to MSRP in an attempt to target another market where in the past, a card will come out, and within a year, it would drop to around 65% of its MSRP.