Individual Shipping Cost: More than one of the same item

[ridexbuilder]

Needing a hack for this (or maybe included as standard).

What happens when a customer purchases more than one of the same item with Individual Shipping? The shipping cost is multiplied by the quantity! Not good.

Example 1.
You're doing a special promotion, selling a widget for £1. It's light so you set an individual shipping cost of £2 (you don't know the exact weight).
Customer buys 10 of them. £10 for the widgets and £20 to post - hmmm.

Example 2.
You're selling a large item for £30 and you know that your chosen postal method will cost you £10 for one, though 2 items will be the same postal cost and three will be a bit more expensive.
Customer #1 buys two: items= £60 post= £20 total= £80
Customer #2 buys three: items= £90 post= £30 total= £120

Healthy profits, if you get a sale at all but not conducive to repeat business.

I've thought about hacking in FirstPlusZones but with a modification...
Read in Individual Shipping price and add on a percentage for additional items. Not ideal but certainly a flexible improvement.

Using example 2, with a 25% increase (cumulative)
Customer #1: 2 items= £60 post= £12.50 total=£72.50
Customer #2: 3 items= £90 post= £15.63 total= £105.63

Back to example 1, with a 20% increase
10 items = £10 post= £10.32 total= £20.32

Not the best examples but you get the idea, hopefully.
Anyone done something similar? Thoughts? Ideas? Solutions?