USPS First Class shipping to the UK is approximately $20 for a three pound box.
I would have to actually check my bill, but I believe it was actually more than that, and it wasn't first class shipping.
If your country charges customs fees, they are the buyer's responsibility whether they're included in the price or not. If they were, it'd just cost more up front, but the same either way.
True, but lets say you went to HMV/Walmart/whatever, paid around $60 for your shopping, thinking it was on the expensive side. Then as you are working out the shop, you are charged $25 more to be able to walk outside the shop with your goods, you would be upset, as if you would know your shopping was infact $85 and not $60, you wouldn't have got it in the first place.
Then to make the situation worse, you discover that your shopping has mold and isn't fit for consumption... it leaves a bad taste in your mouth.
Sure, I accept full responsibility for going into the Walmart (in the example) and ending up buying that stuff thinking it was good quality, even if on the expensive side, it was one of the biggest mistakes I did. I just didn't expect to have to pay $25 to walk out the shop with my shopping or discover it wasn't the products I thought it was getting.