I used a Bad Elf GPS with an iPod touch (30-pin connection NOT the newer Lightning connection) for my PCT thru-hike to use Guthooks app and Halfmiles app. Worked great - handy little GPS.
Brand new - the GPS dongle costs $100 (AND THIS IS AN UNUSED AND BRAND NEW BAD-ELF GPS as mine died on the hike and I bought another one after I got home, no packaging or extras)
Looking for $60 shipped CONUS. for the Bad Elf GPS. Paypment via Paypal Personal or add 3.5%.
(edited to remove an iPod which is not being listed)