>but nobody will sell to them.

The self anointed "international community" is only a very small fraction of the actual world. This is typical western hubris and arrogance thinking that everyone will blindly follow them and those who don't, will powerlessly suffer the consequences of the wrath of the west. Russia has money, the world loves money, the world will sell to Russia. Not only that, but there's no shortage of western corporations busy trying to find ways to covertly sell to Russia because that's what they've done to every other pariah state. Russia will incur higher costs to acquire the things it wants but it will still be able to get them and it will often be western companies covertly doing the selling.