Theres no problem with using ceramic in the front and semi-metallics in the back.
For inexpensive ceramics I've had great luck with the Wearever ceramics from Advance Auto, virtually dust free, quiet and stop well for about $45. Napa sells a good ceramic pad but they're about $75 if i recall ...

http://i251.photobucket.com/albums/gg303/ken_buck/volvoimg.jpg

Not a great picture, but these are our 2 Volvos. Both Polar white, both 2003. One is an XC70 (obviously) and and the other is an S60 2.5t AWD. Previous Volvos were a 1993 i think 850, also white, and a 2000 V70.

These 2 are by far my ...

I use it in everything that requires ATF. It works fantastic.