@Raoul41 This sounds like a case of the host either having neglected to update his pricing for a busy time of the year and then trying to ask you to pay more, or there may have been something about your message that he didn't like so he was trying to get you to go away by naming a price he knew you wouldn't accept.
Or maybe you didn't enter the correct number of guests who would be coming? $90/night may have been the price for one person, not for 3, and the base price shown on the listing may be far lower than the price for specific dates.
And to answer your question, no, a guest doesn't have to put in a booking request, as opposed to an inquiry question, in order not to get a reply like you got. In fact, if the host doesn't want your booking, all they have to do is decline the bookng request. I just got an Inquiry last night from a guest who asked if she could have a friend stay for 3 nights of a one week booking, when it clearly states on my listing that I only host one guest at a time. So I just messaged her back, saying no, I don't accept 2 guests for the one room I host, she said she understood, and proceeded to put in a booking request only for the days she wanted to stay on her own. Which i then accepted. No price changing, nothing like that.
In fact, many hosts wish that guests would ask questions about anything they are unclear about, before sending a booking request, as when guests arrive with false expectations, it's not a good scenario for either the guest or the host. If the guest hasn't asked these questions beforehand, the host is faced with having to either accept or decline the booking within 24 hours, even if they and the guest haven't gotten things clear yet.
So it appears that you did everything right, you just had the bad luck to hit on a host who wasn't too nice. It's really best not to just go for the cheapest place, but instead use a price range and then read reviews for the place before considering it.