Don't buy a tv because the HDMI cable comes with it. They're cheap and, for the most part, the quality doesn't matter unless you're needing a very long cable. Monoprice and Amazon have some very good HDMI cables for very little money.
Absolutely. Never buy your HDMI cables (or any cables, really) at a brick-and-mortar. Buy them online, and you'll see how much you're getting gouged on them normally.