I think, if you are patient, the commons and rares will be available at low priced due to the Starter packs only costing $1, many will buy and soon have extras to sell. No harm stacking that extra DEC up into SPS right now and earning some more SPS/Vouchers by staking it in-game.

Or what about one of the resource liquidity pools ?, it's very possible that resources will appreciate thus growing your DEC in the LP and earning fees....rather more speculative though