Well, i've sold the 512x head really quick (people loves them like the ocean loves the water xd), lemme give you more explanations 'bout your counter offers.
I'm gonna invert this and i'll start from the katana, as we both said, it's price vary a lot, and i would say that as a median average price is around 15k-20k since it isn't that popular as some time ago, when everyone wanted one of them.
Now, about the straw hat, i'd like to say that i do the same thing with some items 'cause i keep looking for items to make some profit and as far as i know, the last price i've saw for the straw hat was 7k for about 2 or 3 weeks ago, and that's why i've offered that much, and as i said, i'd never have seen noone trying to buy/sell it excepting the market at the price that i've mentioned
Now, as you didn't countered my offer in purely tcs, i'd have to ask for another counter offer from you. And if you could make a starting offer for the straw hat, maybe we could negotiate easily.
Also, ¿do you have pics of the straw hat?, the only preview that i've seen is the steam one and seems like a cut version made to offer it to the public and i can't see it ingame 'cause i don't have internet connection right now