why are tractors so expensive?

So, in advance of Dave's visit, we decided to buy the posthole digger attachment for the tractor, to help in digging the stump holes.

Then Dad decided to get three differently sized augres for it (8 inch, 12 inch, 18 inch) which he said we need for different jobs.

Then when Dave got there, it turned out the tractor annoyingly was missing the bit that you needed to attach the attachment to! So we had to buy that bit as well.

And when they were in the shop they spotted a Ripper attachment supposedly going cheap, so they got that too.

I swear, this tractor is turning into a money pit. :-(

When they finally got it all connected, they couldn't resist doing some practice digging, so proceeded to dig potholes near the shed. Dave assures me he filled them in again though...