You have some solid and cheap mass-produced options available:

Bayer Contour USB Diabetes stick (10$, will be produced for a long long time, can buy anywhere, and hackable):
http://www.amazon.com/Bayer-7393-Contour-Glucose-Monitoring/dp/B0030HTZII
http://www.youtube.com/watch?v=WP80zk-1E-w
http://stackoverflow.com/questions/6554863/migrating-c-code-that-talks-to-a-usb-glucometer-device-from-linux-to-android
http://img1.findthebest.com/sites/default/files/2470/media/images/Contour_USB_520287.jpg

Alternatively, iRiver (big name), RCA (medium), and Coby (budget name) always have USB stick / LED Mp3 sticks for sale with the same basic hardware repackaged:
(29$) http://shop.iriverinc.com/index.php/media-players/t9/t9-4gb-digital-mp3-player.html
http://www.geocities.jp/teamhasebe/pasocom/parts/elctrncs/t92.jpg
(40$) RCA TH2002 "flip out" mp3 usb stick www.amazon.com/dp/B004FN1AA2/ (usually sold at Sears and Radioshack as well)
http://ecx.images-amazon.com/images/I/41WqyfjowgL.jpghttp://ecx.images-amazon.com/images/I/31IMzkwBrUL.jpg
Cobyxample (usually sold at walgreens/cvs): http://www.cobyusa.com/?p=prod&prod_num_id=10716&pcat_id=2001

If in Europe, you could check out the Energy SistemTM Energy MP3 Stick
http://store.energysistem.com/en/productos/mp3_players/39158-energy_mp3_stick_4gb_1404_mystic_blue
http://www.grupoenergy.com/grupoenergy/images/productos/39158/pllbmnemacdm.jpg

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