First, as a response to the OP when I have had horses for sale, I responded to all emails (no matter how ridiculous) with the price/ price range and some brief details about the horse, such as Dobbin has competed at X, Y, Z, has such and such training, has been successful in X type of program, and something about the horse’s qualities including both pros and cons. For example, Dobbin is bomb proof in most circumstances, but has been most successful with a pro tune up every few weeks, or in a regular lesson program, etc.
I understand your frustration, but at the same time, when I am on the buying end I don’t want to spend time on a horse that is outside my price range. When I have sent inquiry emails, I do usually provide some information about what I am looking for and my price range right up front and I sign the emails with my full name and a contact phone number as well. I even include a greeting such as Hello, or Hello Jane Doe, if the contact name is included in the ad- call me old school.
I am not currently horse shopping, but I have purchased and sold horses in the past few years and have experienced what people here are mentioning from both ends. IMO, no matter what my price range, I would be very reluctant to call on a horse whose ad said Inquire in the price, or private treaty. When I see that, I have a few thoughts right off the bat 1) the seller/ agent may be likely to play games with commissions, 2) the horse will be priced outside my range, or 3) if the horse seems somewhat average to me, the sellers don’t have a realistic view of the horse in question.
For example, I know of horses currently for sale that I know are priced in the low-mid 5 figure range (I know the owners and trainers personally) that are listed as inquire or private treaty. IMO, I don’t think a 20-40k horse warrants inquire or private treaty. In that scenario, I would suspect not putting a price range may discourage some serious buyers. Given that these same horses have been on the market for quite a while, I think it suggests that 1) the current marketing tactic is not working, and 2) possibly the horses are not priced appropriately.