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: 
That used to be true, back in the 1980s, in the Soviet Bloc countries, because:

* blue jeans were *the* fashion trend then and there
* they were not available on the market, *at all* (not "sold out", not "in small quantities", not at all.)
* thus providing an opportunity for home-made imitations *and* for scarce (rare even) black-market goods

Now, that's a textbook example for Economics 101: high demand, extremely scarce supply - and prices shot through the roof, quite predictably: and yes, people were willing to part with a month's worth of wage to get that one pair of jeans (as @M.K. recalls in the comments). So, it indeed used to be true, *literally*: sell a pair of blue jeans and live like a king for a week.

Things that have changed in this situation since 1980s: 

* Everything.

No, seriously:

* Jeans are not *the* new hot fashion trend (perhaps *a* fashion trend, if at all)
* Import is unrestricted
* Supply is abundant
* And that all was true even before I could have ordered virtually *anything* from *anywhere*, directly, through the Internet.

In short, that specific bubble has popped not "some years", but twenty-some years ago; *two* major market changes ("paradigm shifts," if you will) have happened since. It's an amusing historical tidbit, but nothing more.
Yes, real Levi's still go for considerably more in foreign countries than in the US, in official shops. Like 501s are usually under $50 in the US, and over $100 in Australia. This is partly historic, partly due to currency fluctuations and the dollar being down at the moment, and partly due to VAT/GST.

No, you will not easily find someone to buy your one pair of jeans in a random size at those same prices. Wouldn't you just buy them from US eBay if you were them?