Do you always propose all available options?
Sometimes, a client will tell you that they’ve already thought of the easy solution, but that they want you to investigate the more expensive (but more optimal) option - this is so they know much more it would be and can decide which option to go with. They may have already had the cheaper option scoped out by another company.
The trap here would be to the only scope out the expensive option, ignoring quoting the cheaper alternative. Instead, you should scope out and price up *both* options, so that if the client prefers your approach, but thinks your expensive option is not feasible, they can still use you for the cheaper option.
Here's how much the full rewrite of your solution would be: $ XXX
Figure: Bad example – no option to use your company if they don’t want a rewrite
The price to refactor your existing code base would be: $ XXX The price to do a complete rewrite would be: $ YYY
Figure: Good Example – whatever option they choose, they can still use your company