I am anything but a fan of Julien's Auctions. Based on my experience, I would warn people to never do business with Julien's unless they had no other choice.
If there's a rare item that you want, though, sometimes you have to go to the source that has it. Just be super careful that the item is real and as represented BEFORE bidding.
In the case of estimates, though, Julien's is no different than many other auctions. It's common for auction house estimates to be either dramatically low or high, especially on desirable lots. Low is most common.
For instance, Bonhams has a Beatles-signed Please Please Me album dramatically signed in black marker with a caricature added by Ringo at an estimate in the £16,000 range ($20,000).
Even tho Please Please Me is the most common and least valuable band-signed Beatles album, I think that album could easily bring mid-to-high 5-figures. The only other PPM signed in marker sold privately for 6-figures in the early teens. That one was perfectly signed, big, bold and fantastic, but I think this one is even more desirable.
I didn't know there was another signed in marker. Did I miss it or is this new to most of us?
These auctions houses selling (cobains clothing based on a photo isn't solid enough provenance , I mean lets go and buy a pair of chuck taylors and say these were kurts.