Yeah, that's pretty much what you're going to pay for a top-shelf, registered receiver, swing down lower.
Prices on the boards lately have been in the 7000-9000$ range. Figure the higher prices aren't moving as fast (at all?) vs. the lower prices...
There are essentiall four types of MP5s out there:
Original MP5 imported before 1968. Only a few in the country -- going price is like 20k$.
Registered Receiver - started life as a 94. Factory correct in every way, has a swing down lower receiver. 8000-9000$
Registered Sear w/Sear married to Gun - started life as a 94, doesn't have the swing down. A semi pack has been modified to fit the clip on nature of the 94. 7000+$
Registered Sear and sear isn't married to gun. Pretty much the same as above, but the gun is papered as a sbr. allows you to move the sear from gun to gun. Requires two tax stamps. Actually with the sear in the gun, it only requires one tax stamp, but when you take the sear out, you need to have the gun papered as a SBR. $7000+$.
Note there really aren't differences between the last two because you can always "divorce" the sear from a gun if you want to paper the underlying gun.