For whatever reason - sometimes I suspect it is simply a marketing trick to enforce customers and partners to use only their own brand - Panasonic seems to be constantly changing the naming conventions of their semiconductors, specifically power / IGBT transistors.
A Google search for B1DEKQ000003 on Dec 3 2001 would yield Encompass and PartStore at the top, each offering the above said transistor for about $50.
You can't get much specification about the transistor let alone a more reasonable price.
Well of course both exist - substitutes and more reasonable prices.
Take the repair kit for TH-42PX60U's power board:
It has the B1DEKQ000003 (or substitute) and a few other parts on top of that and as of today (Dec 3rd 2011) it is on sale for half the price Encompass asks!
Don't know how it looks on your end, but where I'm from it's a no-brainer.