Is this allowed ?
Bit of a cheek to sell it for more than they paid
Probably not, but people sell stuff on eBay they shouldn’t!
I’ve seen multipacks (not for resale) on there
It’s been listed multiple times with that photo, if they paid for it outright (as you do on the 2.5Gb service), then its yours as long as the contract doesn’t say otherwise.
Its actually a very good router and worth the £100 given it has 2x2.5G ports which is quite hard to come by. A non-Yayzi customer might want it for their internet.
Personally, though I would rather pay £100 for an N100 with 4x2.5G ports and put my own Firewall Operating system on there.
Aliexpress also have frequent voucher sales to knock off a further $15 off that price. I am using one right now with Yayzi having IPfire Firewall OS installed onto it.
You could also look for a Dell SFF PC for £30 and buy 2 10G ports. Although that’ll use more power than a purpose built system