How wonderful your guy is doing so well!
On asking questions so as not to offend ANYONE,
I think that is impossible!! But here is what I do.
First, don't have unrealistic expectations. A lot of times I see "Wanted" ads with a lot of very specific requirements: must be under 30", must be double registered, must have perfect show conformation, must be a black and white frame overo, must be a mare - and must be under $500.00, and must be hauled to my place!!!!!
Puh-leeze...... if someone had such a gorgeous horse it is not reasonable to think they will part with the horse for under $500.00. Keep your expectations reasonable. There are some bargains out there, but you may not get that black and white frame overo with perfect conformation. If you are working on a budget, set your sights on something a little more reasonable.
Try not to be too picky on size, sex and color. There are a lot of really really nice horses out there that no one has bought, because they are chestnut, for example. Or it's a gelding with a fabulous temperament, and everyone wants a mare. Try to be flexible.
Usually I explain that if I am making an offer, I am simply offering what I have, and that I completely understand if the person can not accept my offer. I also am prepared to fully explain the type of experience I have, the type of situation the horse would live in, and whether or not I would ever sell the horse. All of these things can be very important. Also you should be prepared with references!!! It helps to have a working relationship with a vet, and other horse people. You don't have to have bought a horse from them, maybe you worked at their stable or something, but that will help.
If you treat people with respect and consideration, they are usually quite understanding. However if your budget is $1,000.00 and the horse you want is $10,000.00, you might want to pick a different horse. I guess I would not consider that as respectful....... Put yourself in the SELLER'S shoes, and try to think how you would feel if the shoe was on the other foot. That can really put things in perspective.
Good luck, I bet you can find a nice companion for your boy because there are a lot of really nice horses for sale right now.