Had a customer ask if he can get a smaller hard drive in his Performance workstation.  It may be possible, but it's not worth the time and effort required to find out, to do a downsell.  I could have quoted an Entry workstation with a smaller hard drive, but again, I did not want to downsell at a lower price than the Performance workstation that I've already quoted.

Here's the email I sent back to the customer; it might have some nuggets you can use if you run into a similar situation:

It’s a fixed configuration, so no opportunity to customize.  It’s the same computer that someone gets when they buy a new machine today. We buy them by the pallet load and stock them at the Zeiss factory.  Once you receive it you own it, so if you want to customize yourself after delivery, you are free to do so.

It may have more hard drive space than you need today, but you know how things go, over time you’ll fill it up during the lifetime of the pc and eventually, even run out of space on a 4TB drive some day.  For example, my work laptop has a 200Gb HD, and I would have said there’s no way I’ll ever fill that up.  But here I am today at 80% full, so the writing is on the wall that I’ll need to upgrade my work laptop sooner rather than later.  I know that 200Gb does not directly compare to 4TB, but what is good about the larger hard drive on the computer I quoted you, is the computer will have a longer lifetime before the hard drive gets filled up and the computer needs replacement again in the future.