Any 4 piece fly rod outfit is packable. A 9 foot 4 piece rod breaks down to about 30" in total length. I've seen many rod tubes holding 4 piece rods tied vertically to back packs. If you really want to go packable a 6 piece rod is the ultimate but these are usually pretty spendy. I bought one of these in this link for my gf and it is a decent outfit. Shop around and you can probably find it close to the $$$ you want to spend. If you do spend a little more it is probably worth it. This will get you started but for certain any outfit with a four piece rod will let you carry it on a back pack easy enough. And for fishing Crappie and other pan fish I would recommend the 3/4 weight rod.
Fly Fishing Outfits, Essence Outfits - Ross Reels USA / Ross Worldwide
Dan
Alright fish, I know I got something in this boat you'll eat.....Yep, the 'ol boat carpet seat cushion jig does it every time!