function txtPriceMin_onchange()  {
    checkFloat(document.getElementById("txtPriceMin"));
}

function txtPriceMax_onchange()  {
    checkFloat(document.getElementById("txtPriceMax"));
}

function checkFloat(strValue)  {
    floValue = parseFloat(strValue.value);

    if (isNaN(floValue))  {
       window.alert("The value entered is not numeric.  Please try again!");

       strValue.value = "";
    }
}