JSFiddle - React, Tailwind, and code Playground

HTML

<form name="myForm">
<table>
    <thead>
        <tr>
            <th>Key Stage 1</th>
            <th>Buy on Paper</th>
            <th>Buy on CD</th>
            <th>Buy on both</th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>Year 1 All Blocks & Units (15 assessments in total)</td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="0" data-price="2500" />
                £25</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="1" data-price="2500" />
                £25 †</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="2" data-price="4000" />
                £40</label>
            </td>
        </tr>
        <tr>
            <td>Year 2 All Blocks & Units (15 assessments in total)</td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="3" data-price="2500" />
                £25</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="4" data-price="2500" />
                £25 †</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="5" data-price="4000" />
                £40</label>
            </td>
        </tr>
        <tr>
            <td>Give me it all and save some monehhhh!</td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="6" data-price="4750" />
                £47.50</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="7" data-price="4750" />
                £47.50 †</label>
            </td>
            <td>
                <label>
                <input type="radio" name="keystage1" value="8"...

JavaScript

var frm = document.forms.myForm;
frm.onchange = function(e) {
    var tot = 0;
    for( var i = 0, l = frm.elements.length; i < l; i++ ) {
        if( frm.elements[i].checked ) {
            tot += parseFloat( frm.elements[i].getAttribute('data-price') );
        }  
    }
    document.getElementById('total').value = ( tot / 100 );
}