If you do a search for spy pen camera on ebay, you get many results for the same. So which one is the best with regards to 'the amount of time you can record at one go (one single charge)' and pic quality. Need to record lectures, so will need good battery power.
eg:
eBay India: Pen Spy Camera Hidden Cam MP9 High Quality AVI 2 GB (item 170444477891 end time 17-Feb-2010 18:33:34 IST)
eBay India: Spy Pen Camera And Voice Recorder With 2 GB Memory (item 250582010492 end time 19-Mar-2010 12:26:06 IST)
Edit: One of my problems deciding on which one to buy is that the 2gb ones are sold by 'powersellers' (you can trust these guys more than the others) and the 16/15gb ones are sold by people who have hardly received 7-8 feedbacks.
eg:
eBay India: Pen Spy Camera Hidden Cam MP9 High Quality AVI 2 GB (item 170444477891 end time 17-Feb-2010 18:33:34 IST)
eBay India: Spy Pen Camera And Voice Recorder With 2 GB Memory (item 250582010492 end time 19-Mar-2010 12:26:06 IST)

Edit: One of my problems deciding on which one to buy is that the 2gb ones are sold by 'powersellers' (you can trust these guys more than the others) and the 16/15gb ones are sold by people who have hardly received 7-8 feedbacks.