This. A manager told me once that these kind of things are very easy. Just look at it as if you offer a menu. You have a starter, a soup, main course, desert, coffee and wine during the meal.
You tell them the cost and then thye decide if they want the whole meal, drop the starter, or the soup or the wine or whatever.
The hard part is to stick to your price. Do not be tempted to give the whole menu for the price of the menu without the soup. So you need to have good knowledge of the pricing and be able to defend those prices.
Be prepared for all the questions. e.g. but what if we use cheaper hardware? That should already be part of the menu.
If you are smart about it, you have three prices. The cheap one where everything will fail, the perfect one that is WAY too high and the one that you want to sell to management, because you know it will be the best because you did your investigationand you have the experience they hired you for.
I have been in meetings where the CEO said basically: Seems very clear you know what you are doing, so do whatever you think needs to be done. That did not mean a free for all, it ment that the decision was well thought out and all (as in the huge majority of them) questions were thought of.
So yes, let them decide and help them make that decision and when they choose to have no maincourse, make it clear that they will go hungry at the end and that ordering extra food later wil take longer and cost more as the chef is already gone home.