Sorry for the lack of specifics there! My point is:

Price inflation is not only derived from the market price of whatever it is you're exchanging a currency for, but it is also derived from the value of the currency 'itself', meaning the rate of monetary inflation along with supply and demand of that currency.

In other words, prices of good/services (price inflation/deflation) are reflective of the exchange rate due to FX trading and the Bitcoin generation rate due to mining (monetary inflation).

So, 'something' worth BTC1 can 'deflate' in price to BTC0.5 if any or all of these market forces apply to it:

1. The currency exchange rate of whatever that 'something' is usually traded in doubles (BTC/USD increases from $1 to $2 per BTC)
2. That 'something' becomes cheaper to make (greater supply) or needs to stay competitive in price (weaker demand)

Keeping in mind that the currency exchange rate or PRICE of Bitcoin (force 1), is determined by the value of the currency, which is the SUPPLY and DEMAND and so on and so forth as explained in the OP...

Price inflation would be the opposite.