Ok, so obviously I didn't mean go and look at an 18k horse and offer 2k, but I see nothing wrong with looking at a 4k horse and offering 3k, I've had it done to me enough times.
totally agree with exacerfan. Im all for making a sensible offer but i usually ask on the phone if they are open to offers. If someone had a limited budget I would expect to be told in advance this fact, to give me the decision to show off the horse. When selling, a lot of time and effort goes into getting the horses ready, swapping work, perhaps arranging childcare etc and I would then be furious to show off my beautiful horse to find that the purchaser only had half the asking price. Time wasting goes both ways. at least if you ask up front you know if there is a deal to be done and both parties are prepared.