the big Port of Siuslaw triple launch is on Harbor St. and it is free but if you park in their lot, which is full now just after sunrise, it is $2. Otherwise you find the closest street parking and walk back. this is the furthest west launch.
Siuslaw Marina & RV Park has a launch at Cushman by the RR bridge and I think they charge $5.
up closer to Mapleton there is an ODFW free launch at Tiernan, no dock, fairly steep but easy to use except at very low tide.
at Mapleton there is a Lane County Launch at Steelhead Dr. right beside an RV park. no dock but a walkway goes out beside the launch so you can hold the boat while someone parks. free to launch but there is a fee to park.
my suggestion if driving over on 126 would be to launch at the Siuslaw Marina, puts you right on good fishing without the potential chaos of the Harbor St. launch...
cheers, roger