Yes they are the right ones but you will need a few other parts too as I bought a job lot from withams last year for my 110. And I had to take a couple of bits off my old SU's as the new ones didn't come with them.
They are about the right price, the ones I had left over I sold on and got just under that price for the 2 pairs I had.
As for the guy i have no idea how good he is. They do look like the ones from withams tho he must have bought a job lot like what I did.