The one in my safe is a USC with an HK UMP Barrel, Hera grip and ACR folding stock, 2 extra mags. In the end taxes and shipping I'm in for $4900. Although the Hera and ACR route is not authentic UMP, the Hera and ACR does deliver adjustable length of pull which a UMP stock will not. The lower being still set up for single stack UMP mags is to me a benefit. The longer larger UMP mags make prone or bench shooting a pain and the smaller 5/10 USC mags seem just right (my wifes gun and she usually shoots off a bench due to her poor health). Both have to be pinned to 5 anyway so we stuck with it. Had a B&T flash hider on it but that fell apart so don't bother.
All for the pleasure of yelling Yippee ki-yay, motherphucker and slapping that handle down.
Moe