You can purchase these at elementsetn.com.
But....I've been looking at the different commodity ETN's for a while now. I find I get stuck on several points:
Roger's elements funds (actually ETN's) are new and so are very thinly traded. For the agricultural one (the one I'm most interested in) the ETN is not dispersed until 2020 (as I recall). So then you have to hope that the ETN becomes large enough to develop a trading market (unless you have $5M in it in which case they are obligated to redeem your units (shares)).
The prospectus assumes it will qualify for long-term capital gain but that does not seem to be the direction the US IRS is heading.
I think I'm most concerned though that the ETN's of Roger's and others are UNSECURED debt! I'm fine with going long on something and taking a loss; but I'm uncomfortable when I have no guarantee that the financial entity taking my money will be able to pay what is owed to me. Now admittedly one of the larger commodity ETN's (not Roger's) is backed by Barclay's Bank and Roger's Elements products are backed by SEK which the prospectus says is owned by the Swedish State, but still....
I like Roger's views very much. I do believe agricultural commodities are a worthwhile investment for a number of reasons. It's just difficult to find a good vehicle. I go back and forth between something like MOO or RIJA (if it becomes larger and if I learn more about SEK) or buying calls in the commodities market. I have been hoping for some agricultural commodity investment that would qualify for LT capital gains but I don't think I'm going to find one. The longer term calls require an annual mark-to-market but that still is better tax-wise than the current direction the IRS seems to be heading.
Just my thoughts.
Don