Been doing it for years
I've frequently used 2nd user kit, at one point a previous employer was getting 2nd user kit for pennies in the pound.
Dell desktop £39.00
r710 Servers £500
MD3000i £2000 (ish depending on disks)
We built up a good working relationship with a reseller, and made damn sure our backup strategies worked (LTO5 Tape drives £500)
Occasionally projects required a longer lead time, while resellers hunted down the kit we required.