You want to compare a market of goods with a currency market?! What you said looks like you're talking about oranges or potatos, there yes, quantity affects price. For currencies, which is what bitcoin is, such rules don't apply. An 1 usd doesn't cost more or less to produce than 100 usd.
Because of its deflationary nature bitcoin is more akin to a commodity than a currency... You don't just print bitcoin when you need more bitcoin. You need to invest in mining equipment and electricity.
Tacotime - a falling difficulty does not compel a lower price, nor does a rising difficulty compel a higher price. Price is set by the supply of coins for sale and quantity of buyers, that's all.
If the supply of coins for sale is not affected by the difficulty, and the quantity of buyers is not affected by the difficulty, then the difficulty doesn't matter.
Right, but the speculator is over time not likely to be stupid and purchase something for $5 that only cost $2 to produce. These are common markups for businesses that have transportation fees, employees to pay, locations to maintain and pay taxes on... they don't make sense for something like mining. The bottom line is: Why would anyone pay for this?