SupaDupa does not officially support Gift Vouchers, but there is a way to implement them using the Coupons feature if you are smart and flexible :)
Here is the idea:
Create a "Gift Voucher" product, with product variations for each of the different amounts available that people can purchase from your boutique like a regular product.
When someone purchases the Gift Voucher, go into your admin and create a new Coupon limited to 1 use, and not restricted to any products.
Email your customer the newly created Coupon Code, which they may then pass on to their Gift Voucher recipient.