Use the Currency standard format string along with the string.Format method that takes a format provider:
string.Format(new System.Globalization.CultureInfo("en-GB"), "{0:C}", amount)
The CultureInfo can act as a format provider and will also get you the correct currency symbol for the culture.
Your example would then read (spaced for readability):
<td style="text-align:center">
<%# string.Format(new System.Globalization.CultureInfo("en-GB"),
"{0:C}",
Convert.ToSingle(Eval("tourOurPrice"))
/ Convert.ToInt32(Eval("noOfTickets")))
%>
</td>
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