I strongly suspect the problem is simply that the current culture of the thread handling the request isn't set appropriately.
You can either set it for the whole request, or specify the culture while formatting. Either way, I would suggest not use string.Format
with a composite format unless you really have more than one thing to format (or a wider message). Instead, I'd use:
@price.ToString("C", culture)
It just makes it somewhat simpler.
EDIT: Given your comment, it sounds like you may well want to use a UK culture regardless of the culture of the user. So again, either set the UK culture as the thread culture for the whole request, or possibly introduce your own helper class with a "constant":
public static class Cultures
{
public static readonly CultureInfo UnitedKingdom =
CultureInfo.GetCultureInfo("en-GB");
}
Then:
@price.ToString("C", Cultures.UnitedKingdom)
In my experience, having a "named" set of cultures like this makes the code using it considerably simpler to read, and you don't need to get the string right in multiple places.