The answer to the question is more difficult than just a dollar amount.
Some Hammerschmidt horns have very bad intonation. That can be improved, somewhat, but not necessarily fixed. While all of the staff here at the WF will tell you it's best to try a horn in person before you buy it, this is a make where we say, "Unless you can try it in person, don't buy it."
So, if you have a horn identical to the above and it plays beautifully, I don't see a problem for the $1000 range. If it doesn't, well, maybe a couple hundred.