What are some of the best 2nd-hand mining rigs at the moment around the 100usd mark?
I'm going to choose Bitmain Antminer rigs more than any other mainly because of "stability."
As for "2nd-hand" rigs, that is putting a lot of trust in the seller that all is okay with the 2nd-hand rig.
The best thing going at the moment for close to $100.00 USD [AND IT IS BRAND NEW] would be the NEW Bitmain Antminer U3 https://www.bitmaintech.com/productDetail.htm?pid=00020141017110427977rQGR3pcf06BE
$56.00 USD for each U3. You can get two of these for $112.00 and have a total of 126 GH/s.
Yes, you could buy a "used" bitmain antminer S1 on eBay that has 180 GH/s but you also need to purchase a PSU. That would put you over $100.00 or right at it.
The new U3 also needs a PSU but only requires one (1) PCIe to power it. Depending on the PSU you get, you can power 2 to 6 Bitmain Antminer U3's.
Also, the new U3 is NOT stand alone. You need cgminer to run this. If you are not cgminer literate, as I am not, you may want to get an S1 on eBay from a reputable seller.
Antminer U3: Decentralization continued
Bitmain are committed to furthering the decentralization of the bitcoin network and providing quality products to consumers. In light of this, Bitmain is proud to announce its latest miner, the U3 USB miner.
The U3 utilises 4 of Bitmain’s latest generation BM1382 chips in high quality, domed case.
Batch 1 will go on sale on Oct. 18th Beijing (UTC +8 Time Zone). The 1st Batch of U3s are priced at 56 USD per unit (excluding shipping), with dispatch estimated Nov. 5th. A minimum order quantity of 60 is required, each extra units added must be the integral multiples of 20.
* Hash Rate: 63 GH/s at 0.75V
* Power Efficiency: 0.8 Watt/GH/s on wall at 0.75V
* Voltage: DC 12V input, 6A
* Chip Quantity per unit: 4
* One 80mm fan
* Noise: ~25 DB at 25 °C ambient temperature
* Hashrate and VDD core voltage can be adjusted via cgminer command line
* USB connection
* 12V AC/DC power brick of 16A, but power line not included
* Certificate Compliance: FCC/CE
1) Power consumption: Quoted figures depend on your PSUs efficiency, the ambient temperature and the accuracy of the power meter.
2) PSU: You must provide your own ATX PSU with 1 PCI-e connector, or a power line.
Scalable: Multiple U3 miners can be maintained by one controller running cgminer due to its USB port.
Hassle free: Setup consists of plugging in the USB and power cables and running Antminer CGMiner.
Cool: U3s remain cool and quiet due to its 80mm fan which quietly exhausts air out the side of the case.
Stable and Accurate: Based on the tried and tested BM1382 chip, the U3 is extremely stable and is able to run 24 hours a day without problems.
The refined design of the U3 allow it to blend on any desk or shelf without standing out.