I bought two 30L barrels from Sawtooth Outfitters a couple of months ago (October maybe?) at $30 plus shipping each.  They are the type with the external fold down black handles that some places are charging over double that for them.  The barrels are great and I got great service from the folks at Sawtooth.  They are in in Toth, MN off the Gunflint.  The 60L is listed on their site at $50 ea.  I'm looking forward to taking them up to Wabakimi next summer.  BTW....two 30's will stack on their sides in Granite Gear Superior 1 - but NOT side by side.  They WILL, however sit side by side in a Granite Gear traditional #4 with plenty of room.  I got a great deal on a used Superior 1 - a certain outfitter assured me they use them for that and they fit just fine.  They don't and now I have both packs.  They are still great packs and I will keep them both, but just wanted folks to know from experience what they do fit in. 

pd