Not that simple though. More efficient producers can sell their stuff for cheaper, you keep those out of your country and costs skyrocket.
In the end what you'll get is a tariff war, just as other countries would find it harder to sell to you, you'd also find it harder sell to them.
Yeah, I guess that's also something to keep in mind. Some countries could retaliate. If you ban their exports to your country, they may ban your exports. The best way to bring money seems to be to export. I know that some countries already do something like the OP described. Brazil has very high import taxes. It's usually better to buy things made domestically there than imported things. The sad thing though is that many things are not made there, like computers. Brazilians constantly buy their electronics in other countries to bring back home. This makes life more expensive for citizens and less convenient.