An option for filtering the grid is to add a list of filters to a column in XAML. For example, the following markup adds three filters in a numeric column including a custom filter called RangeFilter:
<c1:DataGridNumericColumn Header="Range filter" Binding="{Binding StandardCost}" FilterMemberPath="StandardCost">
<c1:DataGridNumericColumn.Filter>
<c1:DataGridContentFilter>
<c1:DataGridFilterList>
<local:DataGridRangeFilter Minimum="0" Maximum="1000"/>
<c1:DataGridNumericFilter/>
<c1:DataGridTextFilter/>
</c1:DataGridFilterList>
</c1:DataGridContentFilter>
</c1:DataGridNumericColumn.Filter>
</c1:DataGridNumericColumn>
You can find a sample in $\Silverlight\Main\Samples\SL\C1.Silverlight.DataGrid\C1DataGrid_Demo, file Filtering/CustomFilters/CustomFilters.xaml.