Used Tractor Values

I am thinking about selling two of my horses and wondering how much i should charge for them…
My Chevy Blazer- A 9-year-old quarter horse gelding chestnut with a white blaze and four white feet- a wonderfully calm horse allows children of all ages lead him and ride him, he rides, jumps, shows, drives, and baby sits. he neck reins and goes off of leg cues with or without a bridle, he has jumped 3 ft easy and could go higher, he has shown and placed well and keeps a great personality towards everything. He drives quietly and learned in only a week (and a ten year drives him now) nothing gets this horse started and is fine around tractors, dogs, balloons, kids, and baths. I don’t have to work him every week and he will preform great just like if you were to work him every day. If you do work him everyday he will need grain… He is an amazing horse and i am selling him because i can’t afford him for another year of hay. He is a very easy keeper and doesn’t need shoes.
Ebony- a Morgan/Saddle-bred mare 14-years-old beautiful seal brown (black) two white back feet- Very beautiful flashy mare rides and drives she has amazingly tough feet and handles well for farriers (blazer does too) she is up for sale because we don’t have the time for her

I know this is a very strange question, but I’m at the end of my rope.
I am looking for a print – I don’t know if the original was a photograph, or a painting – of a team of horses or mules pulling what I think would be an older Case or IH (red I think) tractor out of the mud.
I know I have seen it, but can’t remember when or where!
My daughter grew up using a team of mules and now is driving computerized equipment. I would like to frame this for her up coming wedding.
Any help you can give me, or direction would be greatly appreciated.
By the way, she and her fiancée use exclusively IH machines on their farm and so this would be a wonderful surprise for them….they both have a great sense of humor.
Thanks for any assistance you can give me.