Hi Babilonian -
For last 2 months, the best price on a new rig delivered to your door has been that Antminers from Sushi or directly from Bitmain. See group buy page. Last price was 1.45 BTC for a unit that you can overclock to 200 Ghash an they run faithfully.
https://bitcointalk.org/index.php?topic=448425.0http://sushi-review.com/Sushi is a proven seller and delivers the goods.
Even at these low BTC price of 1.45 BTC for 200 GHash, it is difficult to get an ROI but that is about as good as it gets right now. Look for Sushi to return next round with even lower prices. Perhaps 1.2 BTC or lower per unit.
You can pick up used equipment, but I would not buy it unless you can meet or beat the Antminer value.
Exception is maybe if you can find someone willing to part with their newer technology KNC or Cointerra machine for a good price, since they are more power efficient. But those rigs are going to be more expensive.
Happy Hashing