$25 for a shimano tdr, and get the litest action they have for your length. Nothing more is needed for downrigging. I stay away from the Med Heavy or Heavy rods cause MOST fish you catch won't be 25+ lbers, and the lighter action will keep the release from letting go by msitake at 120'...then you have to reset everything. I use 8'6" to 10'6", length up to you.
Get 2 TDR's for half the price of a $100 rod! Most places will do a price match if that saves you from running around. Check John's....$23.95.