The websites just work out the exchange rates for you on the fly.
For example, I just Googled "Turkish real estate" and the first website that came up was one called Antalya Homes.
On the site If you click on the different flags then you get a text in different languages.
Likewise, they have a button to swap between currencies as well - so you can see the price in Lira, Euros, US Dollars or Roubles.
Website designers have realized that people from different countries speaking different languages and using different currencies are looking at their websites and so these things simply make it easier for people to use the website.
On the other hand, if you're dealing with an estate agent that only talks in pounds (or Euros) then you are probably (or, at least, may be) being ripped off.
Big thanks from Antalya Homes to TonyBe. for the nice words about us in The Guardian Newspaper.