Ipod touch extra battery pack

[garlicbread22]

Hi
I have an ipod touch 2G and im going to australia at xmas so I want some extra battery time for the flight! Could anyone recommend anything? The options seem to be either just like an external 1900mah battery like this;
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=120616394190&ssPageName=STRK:MEWAX:IT

or a battery case like this;
http://cgi.ebay.co.uk/Mophie-Juice-Pack-Air-Battery-Case-iPod-Touch-2G-3G-/360317200674?pt=UK_CE_MP3Access_RL&hash=item53e4942922

I'm basically wondering which will give me the most time and if the case is work the extra money, as i could get like 4 external batteries for the price of that (I'm not saying that's what id do)

there seems to be a lot of techie people on this forum so does anyone have any recommendations?

thank you!