Haha! Sorry ah... no lobang. =) I did mine myself, and I won't say it's too hard... but neither will I say it's too easy. I mean, to me it's easy la... just dismantle carefully then fit back mah. But different cameras different layout, so I can't say I'd be successful with all cameras.
I think your F31fd & FZ18, don't modify la. If I were you (but I'm not), I would look for cheap 2nd hand cameras with good functions too... so that even in IR, I can manipulate my picture at the time of exposure. If I had the money, I would go for reasonable MP, long zoom, IS, good performance at high ISO, hotshoe... that kind of thing. But I had money constraints and couldn't justify buying another camera to modify. Since my mju:800 has been sitting around for so long without use, I decided to use it lor. 8MP, 3x zoom, A & S mode... pretty usable high ISO for 4R prints, weatherproof (which now that remains to be tested)... good enough for me for my first IR cam. If I fall head over heels in love with IR, I'll consider getting a Lumix or Fuji prosumer to mod.
So... what're your thoughts? Haha! Various Cash Convertors have quite a selection. U just have to make sure you get one reasonably priced coz their prices are usually crazy high. Or just Yahoo! Auctions or eBay! B&S also has a good selection... =)
Damn... I'm super lor soh...