There are numerous potential solutions to consider. I attempted to maintain the HTML markup as much as possible but did have to make a slight modification.
Additional id selectors could be beneficial, although I made an effort to preserve the existing markup structure.
$(document).ready(function() {
var $speed = $('#speed');
var $currencies = $('input[name="radAnswer"]');
$currencies.on('click', function(event) {
var $parent = $(this).parent();
var currency = $('.valName' ,$parent).text();
var amount = $('.cost' ,$parent).text();
$('.resultPrice sup').text(currency);
$('.resultPrice span').text(amount);
});
// Increase amount
$('.up').on('click', function() {
$speed.val(Number.parseInt($speed.val()) + 10 + ' GH/s');
});
// Decrease amount
$('.down').on('click', function() {
$speed.val(Number.parseInt($speed.val()) - 10 + ' GH/s');
});
})
.priceBlock {
width: 80%;
border-radius: 4px;
background-color: white;
text-align: center;
box-shadow: 0px 0 40px 1px grey;
-moz-box-shadow: 0px 0 40px 1px grey;
-webkit-box-shadow: 0px 0 40px 1px grey;
}
.priceHeader {
text-transform: uppercase;
font-size: 20px;
background-color: #f7963b;
padding: 20px;
color: white;
border-top-left-radius: 4px;
border-top-right-radius: 4px;
}
.priceContent {
padding: 0 15px;
}
.priceContent form>p {
line-height: 3;
font-size: 12px;
}
.priceContent input[type=radio] {
display: none;
}
.priceContent label {
cursor: pointer;
color: #0a1612;
font-size: 16px;
margin-right: 15px;
}
...
<button type="submit">Buy</button>
</form>
</div>
</div>
</div>