Pay him what he gave for it when he bought it.

Think of the money he spent on you.... :)

You did not mention what year the Conquest is.

But some info for comparison. A 2008 Conquest starts at $5,000.00. I own a 2006 Conquest and paid $4,500.00.

So given the history of Simplicity's and their longevity, I would second rcbe's thought, "Pay him what he gave for it when he bought it."

Enjoy the journey.
eal51 in western CT

There was a post here last week about the price of a used Simplicity Conquest that is remarkably similar to this one that you may want to use as a reference point . Link below .

Here is a link that might be useful: Fair price for used Simplicity Conquest

I'd guess the tractor is 6-7 years old with the 16hp Vanguard. I bought my Conquest with a 20hp in 2005. I beleive they had the 18h in them for a few years prior to the 20.

I paid $4400 for my Conquest in 2005 with the same options as the one you are referencing (except for the 20hp engine in place of the 16hp --which is probabaly the same engine anyway). I'd say if they paid more $4400 for that in 2002 they didn't get that good a deal on it. So at tops they should have spent no more than what I paid. I seriosly doubt they could get half of that for their 5-7 year old Conquest on the open market. I've seen some Conquest's and Prestige models sell on ebay for not much more than that and they were 2-3 years old.
Machines like these just don't hold their value. John Deere's hold their value as well as any and even they drop quickly.

Given that, it's your parents, so I'd let them set the price. You may over pay for what you can buy a comparable machine, but you know you bought it from a good source. Don't want to deal to hard with the folks.