I don't really think what you said was rude, but maybe wording it a little differently would have been better. Maybe next time either make a counter offer of closer to what you are looking to spend. Or, if you are really far apart on what you are thinking say something like "Thanks, but that's a little more than I was hoping to spend".
BTW, I don't think the response that you got back was at all rude. You said his price high, and he basically told you that his price is what he needs to make it worth it for him to sell her.