"An order [for costs against a defendant] should be made where the court is satisfied that the defendant or appellant has the means and the ability to pay. The order is not intended to be in the nature of a penalty which can only be satisfied on the defendant's release from prison. ...." "14. .... It is a well-established principle that financial penalties should be imposed and financial orders made only where there is some clear prospect of means available to satisfy them. We well understand the learned trial judge's wish to ensure some contribution from the appellant towards the costs of his prosecution, but in our judgment there was no or no sufficiently clear prospect in the appellant's case of the necessary available means to satisfy the order. For that reason, in our judgment, it was wrong that the order should have been made ...."