ROTS Tsum-Tsums from Disney are scheduled to drop April 4. There are only four in this set instead of the usual seven: Vaderkin, Grievous, an AOTC era clone trooper (?!), and Obi-Wan. No word yet on whether there will be t-shirts. Check out a photo of the set here.
LadyJediScientist found a bunch more independently-produced prequel items:
House Organa necklace
Padmé eyeshadow set
Funko announced its first wave of SWCO Pop exclusives. There is one prequel Pop and that is a hologram Qui-Gon:
Han Solo not included. Apparently more exclusives will be announced. Funko says some will be “shared exclusives,” meaning you will be able to buy them elsewhere but they’re not saying yet which ones. If you’re going to SWCO, you must enter a lottery to get a crack at buying any of the exclusives.
Update: Funko will also be producing a 442nd Clone Trooper for SWCO. If you’re not going to the con, the clone trooper will also be available from FYE and Holographic Qui-Gon will be available at Target.