My point was:we do not have much choice in this large storage department.But I will suggest some more options:
have you heard about Vosonic?Vosonic8870 multimedia storage viewer? it is mainly for photo storage,but this latest model is...multimedia.
They sell it empty or with HD up to 500 or 600 G.SQ? - you have to judge it yourself,battery life is not so long,however they use standard batteries from Fujitsu,so you can have spares.
It is not very expensive.(empty - 250$).Similar device from Epson is much more costly.
Another option: popular chinese PMP with OTG function(USB Host).Some of these pmp have quite good SQ - they use Wolfson audio decks.
My friend connected 250G HD to it.You can try 500G.This is cheap!100$ only with 16G internal memory.The problem is...power.You have to power HDD and pmp.However you have 3 pockets
in your jacket/coat - one for pmp,one for HDD,one...for battery pack;connected around you.So,its possible to use such instalation in mobile situation.
Cowon still sells A3 with 80G HD.It was state of art device not so long time ago.
But I think,that we should simply wait till the next spring and we will get 160G in solid state!
For now,I sugest you SansaClip+ in rubber skin and set of SD cards.My own Clip works now with 32G card.
Why rubber skin?You can keep your cards under it.
And it is so small,that you can carry it in your shirt pocket,very close to your ears.Buy 2,you will have 80G.
I like my X7 even more..really..
Cheers!