there is no way he could put this tire package together for $1800.
Here is a price on just tires (one of the better I could find ) $359 each = $1436+ $213 Shipping, so call it $1650 in tires alone.
Nitto Trail Grappler
My buddy at Town Fair Tire checked their price on them for my buddy in a 295/65/20, and they were $408 each at COST. And thats not even a 35/12.50 tire. Internet is usually cheaper than local, even at cost, aside from shipping.
18x9 KMC XD Spy -12 offset $220 each including free shipping = $880
XD Wheels Spy 797 Gloss Black Machined 18x9 XD Spy Gloss Black Machined XD79789055312N KMC XD Series Wheels & Rims
That puts you at $2529 JUST in tires and wheels. Add in another $200 for OEM TPMS (not a cheap aftermarket set), say $20 for Nitrogen fill, and then lug nuts, mount, balance....$1800 is not going to happen. Could you do 20" rims (Not XD) on 35's (Not Trail Grapplers) for $1800? maybe. Could you do this wheel and tire package for $1800 in the 18" that they are? not even close. This package was a $3000 package, set and done, might be able to hunt it down in the 2800 range. But $1800 isn't going to happen.
Now if you are interested, I could definitely move considerably on the price because thats a beautiful OEM set you have, I would definitely be interested. But I wouldn't do a straight up trade.