Actually it's the miners that determine the minimum price. Bitcoin could never trade for just a few dollars with the difficulty at its current level.
The price shot up from speculation, and miners brought it back down, but miners also keep it above a certain level. In the end the real value of a bitcoin is the amount of electricity it takes to mine a bitcoin. If anybody could mine a bitcoin for $5, then nobody would pay $200. But they can't, so they do.
When it costs $1000 in electricity to mine 1BTC, the price will be over $1000.
No, you've got it backwards. Miners do not determine the price, they react to it. The price/value of BTC determines the mining effort. The Bitcoin network difficulty would never be at its current level if Bitcoins weren't so valuable, it's that value people seek and thus build massive farms to try and collect it. When the mining reward decreases, so will the mining effort, and thus so will network difficulty.
I can see why someone who purchased BTC at a higher value would be reluctant to spend them today, but in the end it is a currency and if you're not spending it then what are you doing buying it? It should not be purchased as an investment, which I think a lot of people do. Instead of "buying" BTC it should be looked at as "exchanging" one currency for BTC. The volatile nature of BTC makes exchanging it profitable in some situations, sure, but I think that's a narrow minded way of looking at it. No reason to buy BTC unless you plan to use it.