still no joy :/

anyone else have any advice?

Are you on Modem Firmware 2.28.00? (Settings > General > About)

This is the method that always works for me.

Install Yellowsn0w.
Reboot twice using BossPrefs.
If you still dont get coverage, Remove SIM and pop it back in.
Try Enabling and Disabling Airplane Mode.
If still no joy, Reboot using BossPrefs once more.
Once you reboot, you should see a Searching.. and consequently coverage will appear.

This always works for me.

Be 100% sure that your bb is uptodate first. Reinstall everyhting, YS 095 and try the above stuff. If it fails for some reason turn off 3G settings and try to get it work.
Does your sim have welcome message or sim toolkit applications on it? Any Pin set?