Generate a column dynamically with JQuery DataTables where table is based on a model - asp.net-mvc

Question

In an ASP.Net MVC application I have a table that's based on a model passed to the view. For this reason, the table is not based on a Json and the fields have no column names that I can reference in the 'columns'[] section of the script (or at least I don't know how!...). Still, the table works fine except that I can't manage to generate a calculated field. In all the various experiments I keep getting a NaN or undefined result, depending on the various attempts, and I understand this is because evidently I'm not referencing the proper data value, but how can I do that if I don't have column names?
The table is properly structured, thead, tbody and tfoot have the same number of columns. This is the html for the table:
<table id="mainTable" class="table table-hover">
<thead>
<tr>
<th>#Html.DisplayNameFor(model => model.Value1)</th>
<th>#Html.DisplayNameFor(model => model.Value2)</th>
<th>test</th>
</tr>
</thead>
<tbody>
#foreach (var item in Model)
{
<tr>
<td>#Html.DisplayFor(modelItem => item.Value1)</td>
<td>#Html.DisplayFor(modelItem => item.Value2)</td>
<td></td>
</tr>
}
</tbody>
<tfoot><tr><th></th><th></th><th></th></tr></tfoot>
</table>
The render function on first and second columns works just fine. The third column is where I am trying to calculate and display the difference between first and second column, and that's where I get NaN or undefined. This is the script:
<script>
$(document).ready(function () {
// DataTable
var table = $('#mainTable').DataTable({
responsive: true,
columns: [
{ render: function (data, type, row) { return data + '$' } },
{ render: function (data, type, row) { return data + '$' } },
{ render: function (data, type, row) { return (row.Value1 - row.Value2) + '$' }}]
});
});
</script>
This is the result I'm getting on this particular attempt. I've tried other versions, unfortunately with similar disappointing results:
Value 1 Value 2 test
200.00$ 100.00$ NaN$
etc...
I have also tried this:
columns: [ { data: 'Value1', render: function (data, type, row) { return data + '$' } } ]
and this
columns: [ { name: 'Value1', render: function (data, type, row) { return data + '$' } } ]
and this
columns: [ { data: 'Value1', name: 'Value1', render: function (data, type, row) { return data + '$' } } ]
but in all cases the entire script fails.
I also tried to assign names with columnDefs [...] but no luck.
Would someone be so kind to tell me what I'm doing wrong, or what I should do to make this work?
Thank you!