OK, I'm considering the plunge into high definition TV. I bought a Sony LCD 50" last year and I have Comcast Cable. Their HD cable box rental is $10.99/month. Are there any other viable options before I place my order for this unit? For instance, can I buy my own HD box? I've seen a few boxes selling on ebay for $250 - $300. For some reason, they're all being sold out of Canada. I'd rather buy than rent.