Concentric_Borders (a free* idea)
There is a marvellous trend towards local produce restaurants, where ingredients have been sourced from within a radius of X. Perhaps we could turn this idea inside-out and force the concept financially?
Surrounding a city (no need for towns/cities, they get an automatic advantage) are concentric rings which act as borders that collect tax. Physical rings are impractical, but virtual rings can easily be achieved in the modern era, especially with the registration of business addresses. Crossing each ring creates a tax impost, and the rate is decided by the inbound region. To encourage local production, the tax is reduced to a competitive level, but the aim is to be as self-sufficient as possible with minimal ring tax.
Consequently the more rings goods pass through, the more taxes will be added to their retail cost. Every producer will be more profitable selling locally.
Suddenly bordering nations will make deals in which ring taxes are high, because they will prefer to keep trade local. Market forces will balance it all out.
Categories may need to be fine tuned. For example, luxury cars could have a high level of taxation, while vegetables could be low. In this age, with computers and so on, the taxes could be fluid and fluctuating...
Seasonal fruit and veges are a great example. Ordinarily local strawberries in season will be cheap, and off-season imported strawberries will cost more. With concentric borders, those imported strawberries will cost even more, and locals will choose a local alternative. Politicians will recognise the need to adjust taxes so that they favour local industry.
This has worked for a few cities in terms of restricting the influx of vehicles. It can work for goods as well.
As an extention, such borders would likely take on greater meaning, and individuality of countries could return. This is the antithesis of free-trade, but in reality the greatest fans of free-trade (USA) still retain protectionalist practices.