Openbox Mini S2 HD .... Around £50-65
is a cheap solution if you don't want to go the possibly better DVB-Card route....but despite recent firmware updates, no idea what else it is supposed to open other than normal public EMU, ie if you speak Russian, plenty of info out there for this box, very little info in english. Just Google, loads of places to buy - even e-bay!
The TM7102 does indeed open powervu but at the moment only with a test patch that Newcamd doesnt work on, cccam doesnt work properly on and 2 of the 4 TNT Sat channels no longer work on the test patch along with Viasat 4.8E SVT and NRK channels no longer working.
I own these two boxes and have PowerVU on both, but there are better solutions for PowerVU out there my friend.