The real reasons for ditching the current economic model are 1) it's broken, and 2) it's not fixable. Basically, it's a miracle of programming for a 32K game, but that's as far as it goes: with all the ship and equipment prices based around it, and around the assumption that you're in a Cobra III, "fixing" it would involve rebuilding from scratch.
Computers from low-tech planet A, next door, earn the same as Computers from high-tech planet B, from way over there. It's part of the ultra-basic trading system. As I said, it's a miracle of programming for its age, but …
First, it is fairly easy to fix, using the existing lore of the game. As demonstrated earlier in this thread.
The game already adjusts prices, but based on only the economy type. Changing this to different factors for each commodity is a bit of work, but entirely in keeping with the original method. Let us start with the most obvious. Luxuries.
Currently they are traded from rich industrial worlds to poor agricultural. This makes zero sense. These should depend much on the wealth of the planet, not its agriculture/industry type. Rich planets should pay well for luxuries. Poor planets would not pay well, but also not have them for sale, so they are not a source of luxuries. You might have rich industrial planets trading luxuries to rich agricultural, but why would a rich agricultural world be mostly devoid of any luxuries a rich industrial might lack?
A better way is to have low prices at rich, HIGH TECH worlds of both economy types, with plenty to sell, and have high prices at rich, LOW TECH worlds that want to buy them.
Or what about Minerals.
the manual states that they are produced in agricultural type worlds. Lower tech industrial worlds would have a good price to be worth sell them to, while higher tech worlds would not. Lower tech industrial use the minerals to produce alloys perhaps, so have Alloys
be cheaper and plentiful at low tech industrial, and to be in demand at middle tech industrial.
Mid tech industrial produces shall we say... machinery. Which you want to sell to the richer agricultural worlds.
Computers from low-tech planet A, next door, earn the same as Computers from high-tech planet B
Is false. The superior quality of computers from planet B are represented in the lower BUY price from planet B, not any higher sell price where you offload them too.
So, who buys computers? Well the best price would likely be in richer, lower tech worlds.
If you do this for all the commodities, spreading the best purchase and sale types around to give an even spread of planets you want to trade with, you now have a system where instead of just 2 types of planet you jump back and forth between, and 1 best commodity to trade every time, you have a couple different viable options to buy or sell goods at every system.
If you do it right, you stop any 2 systems being perfect matches for trade between each other, encouraging the player to search for their own more complex production chains between systems, such as:
Minerals from an agri world.
Sell those at a poor industrial, buy alloys.
Sell alloys at a mid tech industrial, buy machining.
Sell machining at a rich agricultural, it is high tech, so buy luxuries.
Sell luxuries at a lower tech rich industrial, hmm what do I buy? well its not that safe a place, so maybe those firearms look inexpensive...
Do you see how this can work?