Question: Some years ago, particularly before the 1990s, there way a saying in Europe that (paraphrased) you can sell your blue jeans in every part of Eastern Europe and literally live like a king for a week.

Naturally things have changed since then. But is it still possible to do so in any part of Europe?

Answer: 
It used to be the thing to travel to New York for the weekend and come back with a suitcase full of Levi's (nonchalantly avoiding the red channel).

Looking at Levi US and EU\_GB sites, I see the prices for the classic 501 is from $44 or £70 ($112). However, mid-nineties saw the emergence of a large grey market. I guess you only pay the high prices to buy from posh shops. If you are going to try to sell jeans from a suitcase in a pub, you'll have to significantly undercut the legitimate greymarket, and you'll presumably need to pay duty on the imports (don't break the law!).

I understand that in the US Levis are considered an everyday, working brand. In the UK they are considered a fashion brand, so they can command higher prices, and someone has to pay for the advertising. 

[I only wear sensible trousers from M&S.]
Not anymore. Now you'd have to sell a blue auto...

Nowadays you can buy a heck of jeans of various quality everywhere, from marketplaces to supermarkets. The prices in, for example, Poland, are much lower than in Germany, so you'd have more luck selling your jeans in Germany...

Before the 1990s the situation was completely different. Almost everything was hardly available (there are various photos of markes shelves, where there's only vinegar on it). Some products, like jeans, were possible (officially) to buy only for dollars and the average citizen wasn't allowed to buy dollars, so such products were available only to people having relatives in the West, or buying it second hand, for the high price. 

Now most Eastern Europe is in EU, and the rest trade intensively with the west, and the dollars are widely available, as well as the goods from all over the world. And jeans comes mostly from Asia. Such curiosities as internal export (see Pewex) are known only to older people, for the yougsters they are like knights and dragons.