I ordered 3 Amal 1 into 2 cable junction boxes from Burlen Fuel Services in Salisbury recently. The order arrived 6 days later by Royal Mail standard 1st class post. It was a "large letter" size envelope weighing 40g. They had charged me £7.50 for postage.
I send out many similar size and weight orders every day and charge my customers the actual Royal Mail charge of £2.60.
Profiteering on postage is pretty rife, it isn't good for the companies reputation but the man at Burlen was quite resolute that £7.50 is a reasonable amount to charge for post which costs them £2.60 and they have no plans to stop overcharging their customers.
Another company which likes to make a few bob on the postage charges is CMS in the Netherlands who have eye watering postal charges for airmail to the UK.
The other side of the coin are companies like Fowlers in Bristol and Crooks Suzuki in Barrow who's postal charges are very reasonable.
I think more people should question their suppliers on this matter as it seems to be that profit from postage is now accepted as normal business practice.