Reasonable
At a point close to the end of the build I feared I would not be able to complete it which would have been soul destroying. I had a shortage of green 1x1 plates even after using every spare. However leaving a few off here and there and moving some around allowed me to finish it and it is not as fragile as I feared (tip here is to use the spare 8x4 plate to reinforce the rear floor)
Looks the business. Great design. You should be upfront on the spares and extra bricks required.
Why do you have to buy?
Would give 5 stars if it was all free 😕