BTC is somewhat different though. It is divisible to 8 decimal places (infinitely divisible in theory, just need to update the clients). So people can never be "priced out" of the market, they can just buy a smaller slice of the pie if they desire. This is unlike a house where I (typically) can't buy just a fraction of it.
This is a misconception. Despite claims, BTCs have intrinsic value, and while they can be subdivided, a quantity of BTCs is still required to accomplish a particular purpose, just as a house of a particular size is required to accomplish a particular purpose. People don't buy Bitcoins just to buy Bitcoins, they do it with an objective, and if that objective isn't available at the price a BTC is quoted, they won't buy.
The underlying value of BTC comes from the availability of things to buy in the Bitcoin economy. and speculation. Taking the first one first, there's a limit to which people are willing to pay a premium for access to the BTC economy, and if people are paying $10 for something with BTCs they think they can get for $8 otherwise, they won't pay.
Exchange for goods and services appears to be a relatively minor use of BTCs, though, most people that are buying right now are speculating, and as you say, there's no floor below which people cannot buy in order to speculate. However, if people value a BTC based on speculative future gain, they're going to value them less if they perceive their nominal value declining, which is why crashes happen: the expectation of decline causes decline, which causes the expectation of decline. If you have a BTC that you bought for $900, and you offer it for $1000, someone might accept that price if they think they'll profit from it still. However, if a buyer doesn't think he'll profit from a $900 BTC, he won't pay that price, and he'll be "priced out."