1d8 with a bell curve

I think the gaming world is finally ready for this concept, a combination of ideas I've had for years.

I was thinking about the concept of an in-game economy the other day. Where Characters would come to town with a pile of resources to trade, they'd earn credit that could only be used in this town, then buy up new things once they left for trade in the next town.

If each thing is valued seperately but in a range, you could just roll a bunch of dice and the final result would fall into a bell curve.

Scrap metal is worth d8 credits in this town...I'll trade the ten bits of scrap metal on my wagon, and roll 10d8 to see how much they'll give me for it. Maybe (but highly unlikely) they give me less than 20 if they've got a glut of scrap metal in town, it's just as likely they'll give me 70 or more if it's in scarce supply. More likely they'll offer me a value in the mid 40s. 

It works well when you've got lots of items to trade, and the dice average out into a nice bell curve. But what if you've only got one bit of metal to trade? It's just as likely you'll get a high, medium or low result, rather than the push toward those middling values.

Here's my remedy, based on the scoring system of Olympic diving and gymnastics. 

Always roll two more dice than you need to, then drop the highest roll and the lowest roll. If you need one die, you're rolling three dice and keeping the middle score...if you need ten dice, then you're rolling twelve and keeping the middle ten. 

When you're rolling buckets lf dice, the removal of those top and bottom results doesn't do much, but the result is falling into a general bell curve anyway. If you've got a low number of dice (or even only one), the removal of those dice instantly pushes the result from a flat result into the general bell curve progression.

You can see this when you use the "Middle" function on Anydice.com. 

output [middle 1 of 3d8]

output 1d8

I'm only really thinking of this for use in trade goods and bartering comparisons at this stage, because we want a common value and the chance of things being worth more or less (but less likelihood of the further deviations).

It could work with any die size, d8 is just the example used in this post.