There are always many posts asking for the current value of the old BMX bike or part you have found, or are trying to purchase, etc.
The simple answer is we don't know.
As with anything, particularly anything old, it's value is judged by what someone will pay for it today. What one person will pay, is not necessarily what another person will pay. A simple rule of thumb is the value of your item is what you would pay for it.
Search ebay, or here on the for sale forum and you might gather a general idea as to the value of the item you possess. These values change daily, and are unique to each individual based what holds the most sentimental value to that particular person.
All it takes are two individuals going after the same item on the same day to drive the value of any particular item through the roof.
There is no Kelly Blue Book for BMX.