Yes, that would be a problem, but why does this never happen to me?
The first is that I charge a design fee and I have yet to have someone with a $10k budget sign a contract. The second is that I interact with them and determine a subjective budget ... ie, modular block instead of natural stone, or many other hints that you can get out of them.
However, my way is not for everybody. It depends on your market and your client base and whether you make a living on the design or on the build. There are way more $10k landscapes to be built than $50k landscapes which means more opportunity to work and make money. I only design. I am not viable in that market because I can not sell design in that market. You can still make lots of money selling $10k landscapes. I am not marketable as a design only person if I charge enough to make a living. ... but I make a lot of $50k+ landscape jobs for a lot of contractors doing it this way.