I would like to sell three of my mining rigs to a local hardware store however they think my asking price is too high since the hardware is used.

Here are the specs of my three rigs, hope I can get some clear idea of what they might be worth today.

Rig # 1:

Motherboard: Asus PRIME Z270-A

GPU: 8 x Asus STRIX GTX 1070

CPU: Intel Core i3 7100

RAM: Kingston HyperX 8 GB

SSD: Kingston 128 GB M.2

PSU: Coolermaster V1000

8 x Riser cards for GPU

High quality Aluminum Frame

Asking price 5500$

Rig # 2:

Motherboard: Asus ROG Strix Z270F

GPU: 8 x Asus STRIX GTX 1070

CPU: Intel Core i3 7100

RAM: T-Force Dark 8GB

SSD: Kingston 256 GB M.2

PSU: Coolermaster V1000

8 x Riser cards for GPU

High quality Aluminum Frame

Asking price 5500$

Rig # 3:

Motherboard: Asus PRIME Z270-A

GPU: 8 x ZOTAC GTX 1060 AMP!

CPU: Intel Core i3 7100

RAM: Kingston HyperX 8 GB

SSD: Kingston 128 GB M.2

PSU: Coolermaster V1000

8 x Riser cards for GPU

High quality Aluminum Frame

Asking price 3500$

Please keep in mind that the hardware is barely 6 months old and has been running 24/7 obviously.

How much lower should I go? Do I have any room for negotiation?

Thanks!