From the link: "*Please be aware that the bitcoin price is pegged to the US$ and will fluctuate until final checkout."
You won't know until the transaction is complete exactly what the price is in bitcoins. In reality, the sales are priced in dollars, they allow you to pay with bitcoins, and they calculate the exchange rate at the instant the transaction is completed. What you finally pay in bitcoins may be higher or lower than the listed price. Not sure when I'd be in the market for an apartment in Dubai anyway
I'd expect the same is true for the other place you linked to. I couldn't find the info on their site. It actually looks more like they don't have anything you can actually buy there. I looked at the listed price of one of the items. The Hennessey Venom GT sells for $1,200,000 or 1,445.783 BTC. I guess if you want to spend 1,445.783 bitcoins on it you could, but based on today's closing bitcoin price, that would be the equivalent of something over $13 million. More than ten times what it would have cost by just paying in dollars. Let me know where I messed up if I have that wrong.
I guess using bitcoins would make shopping a bit more of an adventure if you want that. From today's chart, it looks like the price of bitcoins in dollars fluctuated by close to 10% today between its high and low prices. I went grocery shopping today. I would have found it aggravating to get to the checkout counter and found out the prices went up by 10% between the time I took the items off the shelf and when I paid. I'll admit it would have been pretty neat to find out everything went down by 10% though.