I recently traded 2 icons for a GNG and I seen in the past week that someone sold one for 125k. Some sellers would sell both the beta Pickle and GNG for the price of 320k while other sellers would consider that each item is worth that much. So it's really up to what the seller think it's worth...you just have to find the right one.
And while I seen pickles being sold for 300k+, I have yet to hear of anyone buying the musicblock for that much.
I paid $10,000 for one in the first week after game opening. I had a feeling it would turn out to be a worthwhile investment. At the time there were three or four of them in the auction for from 10-15K.
Just so folks who might be working really hard to get one know: it isn't a music block that contributes to any of the trophies. So you don't need it for that. Just keep exploring, in every part of the world, to get the trophies. Key music blocks are location specific, so if you're missing some and have yet to explore the swamps, start digging peat, etc.