Because the developer is in Europe. Any developer from another country will have their units from their perspective country.
Once you click it and just before you buy it, the market will convert to US Dollars.
And I would NOT buy beautiful widgets. I would buy Weather Widgets Donate w/ Flip Clock.
Why?
I haven't used Weather Widget Donate but I do use Beautiful Widgets and I think it is great and worth $1.45. I also hear that Beautiful Widgets are going to start allowing skins for it just like Weather Widget Donate.