What they said...
Right near City Hall.
In terms of best cost, any street parking north of Boone is free of charge, but it's a small hike south to the park. In terms of distance, River park square mall (1.25 per 30 min) is probably the cheapest rate in terms of a parking lot. And the mall is across the street from the park. Parking meters are nearby but it's often hard to find an available one. And they don't exceed 2 hours, usually.
Thanks! Your answer is awaiting moderation.