I like that, but include the conditions in the same package. Otherwise the seller may react positively to the number and feel that inspection or valuation protection was added later.
Has anyone mentioned competing interest? Felix can ask whether other offers exist, but should not abandon his ceiling merely because the answer is vague or urgent-sounding.
Make three columns rather than guessing percentages: costs due before moving in, work required during the first month, and optional work. Add the insurance excess and a realistic moving allowance to the first two. Whatever remains is not automatically a furniture budget—it is your protection...
The awkward part is that finding a defect can create an immediate cash need rather than solve the problem. Even a good report will not make the builder carry out disputed work quickly.
I would therefore avoid using the whole available budget on the inspection. Leave enough for moving, service...