Check with some of the smaller electronics shops, they may have a converter or will know where you can buy one. Also check with your tv provider, assuming you have cable or satellite. I had direct tv and their signal is NTSC and they provide a decoder to covert it to PAL.
Also, check carefully the specs on the converter. We got one that did not work with our TV and/or cable. To be honest, we don't know why it didn't work.