Postage is postage as far as I'm concerned, and I don't use it as another income generation vehicle to rip off the customer, unlike many online retailers.
A T shirt plus the bespoke plastic bag comes to around 200 g depending on the size of the garment. The total will therefore be the first class postal charge of £1.26 plus the cost of the bag which comes to a svelte £1.50. You won't often find shipping charges fairer than that.
Bear in mind that this still gives you 50 g wiggle room as you can send up to 250 grams in weight for the same price, meaning that you can purchase some cards as well with no extra postal charge. Cunning eh?
If you are just buying cards I have no option but to charge the cost of a first class letter plus the stiff card backed envelope which comes to 75 p in total. It is therefore in your interest to buy lots of cards, or a t shirt as well as this will save you money. Well, kind of. You know it makes sense!
The same guidelines apply to international shipping with Royal Mail's charges detailed in the table below. World Zone 1 includes the United States and Canada, and World Zone 2 Australia and New Zealand.
Any queries just e mail me. I'm sure we can work something out.