Sellers giving buyers the choice of postage which doesn’t adequately cover the item’s value are idiots sensible
Insurance of any kind is never value for money as the insurer always needs to make a profit.
When you sell something Pay for the cheaper postage option and put the money you save each time aside to cover the loss of parcels if this occurs. You will find that the pot is never empty and can be used for buying shiny new bits at the end of every year.
The reason this works is peoples idea of risk is usually hyper inflated – (I’ve had 1 parcel disappear in 130 ebay transactions.) This is also the reason insurance companies earn squillions. Insurance is basically gambling – but with much worse odds than you get at the casino.
I use this policy for everything I can’t afford to replace – even my expensive bikes. The money I have saved on expensive bike insurance over 10 years is massive – I have used this money to pay for high security ground anchors/ chains etc. but the excess will easy pay for a new bike.