I did in this way:
Assign a customer to a group which I want to display the price. (customer id=4)
Add the folowing to / classes / Product.php
public function getPriceGroup($id_product, $tax = true, $id_product_attribute = null, $decimals = 6, $divisor = null,
$only_reduc = false, $usereduc = true, $quantity = 1, $force_associated_tax = false, $id_customer = 4, $id_cart = null,
$id_address = null, &$specific_price_output = null, $with_ecotax = true, $use_group_reduction = true, Context $context = null,
$use_customer_price = true)
{
return Product::getPriceStatic((int)$this->id, $tax, $id_product_attribute, $decimals, $divisor, $only_reduc, $usereduc, $quantity,
$force_associated_tax, $id_customer, $id_cart, $id_address, $specific_price_output, $with_ecotax, $use_group_reduction, $context, $use_customer_price );
}
And after add in the file / yourtheme / product.tpl
Price group: {convertPrice price=$product->getPriceGroup()}
It took some time to learn the structure, but at the end it work.
Hope that it will work also for you.
Best regards