After looking at his listing, he is adding the grapple and the forks for an additional $1500.
He list it as 45 HP, it's actually 42 (that's engine HP). He is correct when he says, "...no computers or emission stuff on engine." You can look at any xx40 series tractor and also not get into the emissions stuff, that's from 2007 through 2013.
The xx40 series of tractors are what Kubota calls the "Grand L" series. There are many features they offer the other models don't. The Grand series come with adjustable slides on the 3 pt arms, other models have turnbuckles. Doesn't seem like much until you use them. They also have a quick adjustment to lengthen the 3 pt arms for easier attachment to lift pins on attachments, just as an example.
I did a google search for Kubota 4240 and came up with this for comparison. 2007, has 3rd function on it, 1080 hrs. Yes it's more cost, but you can also get insurance through Kubota to cover problems, I think. Also, the price listed on TractorHouse is negotiable, I'm sure. Their job is to sell tractors so they have to have some wiggle room in their listing to make people feel better when they come down some.
The L4200 on FB looks to be a clean tractor, and with the grapple it has a 3rd function on it. That's 1K by itself and it appears to be a Kubota kit, which is nice because it has steel lines not hoses going to the front.
I think his price (on the L4200) is on the high side.
Here's the link to Tractor House and the tractor I was mentioning.
https://www.tractorhouse.com/listings/farm-equipment/for-sale/191500421/2007-kubota-l4240hstc