I have just had a quick look at moneysupermarket most prepayed cards have an initial fee of £4.95,
There are free setups though you pay £10 for the card.
Before getting a pre-pay card; really check the small print.That's usually hidden on websites rather than on the card, packaging or leaflet.
There can be initial charges, charges for topping-up, charges for use, monthly charges for use and also for non-use, cancellation fees, difficulties in obtaining any credit as a refund, plus all sorts of pitfalls and traps deigned to take your money off you. After all, they exist to make money for the companies providing the service. They can work out very costly, especially if used to facilitate a one-off purchase.
It's usually far better to get family or a friend to purchase on your behalf. The order limit may be a problem short-term but that will be a non-issue shortly.