Specifically on the issue, start from here . And then about onchange ...
upd Well what you do yourself. Seriously.
Do not appear in the user interface for radio buttons. The value property only has meaning when submitting a form. It is not a list of informations sent by the radio.
All three and will not be sent. Same radio, they have one name, it means that the value that is selected will be sent. Specify the value for the radio button and that's it.
upd2 . re-read the comment. value, which is considered to be yours and you write it in the input type="text"
's write to the values of these radio buttons. For radio buttons it is necessary to establish compliance with the prices. set id for them, for example:
<input type="radio" name="chb[]" id="r45" value="0"> <input type="radio" name="chb[]" id="r60" value="0"> <input type="radio" name="chb[]" id="r90" value="0">
when calculating, write in them the corresponding values in the script:
document.getElementById('r45').value = 1000; document.getElementById('r60').value = 1500; document.getElementById('r90').value = 2000;
when sending a form, on the server, catch what is written in chb [], there will be a selected price.