Plumpy Glasses were retired in August 2007. Wacky Jeans were given out as a Click-To-Win item somewhere between October 2006-November 2006, I believe. Plumpy Glasses are now considered priceless because it's been two years since they've retired, but Wacky Jeans are still worth more because they were considered priceless at least a year earlier.
I would think that Plumpy Glasses for Wacky Jeans would be a ripoff, but it also depends on the person. Some might value the Plumpy Glasses higher than the Jeans.

However, I would think that most people would think it's not fair.