Whats a fortune? Like said above, need an actual budget. Some clients who really enjoy a nice landscape wouldn't bat an eye to a $50k proposal, for them "fairly basic" may be some specimen plants that are already 6' tall. While their next door neighbor in an identical house may want the minimum and think that $10k is a fortune to spend, they may be happy with all 1 gallon plants that they need to wait 5yrs to grow in.
Why do people not respect us as they do other tradesmen? Because every Tom, Dick, and Harry doesn't think he can be a plumber or electrician!