That style of takedown came out in the mid '70's, when bear was focusing on their new compouind lines. They were a lot cheaper to make than the Kodiak Takedown, wood and magnesium riser series. You bow was a 1976 model, in commemration of the bi-centenial, There were many different names and models of them with the only difference v=being thecolor or the riser, and the name. While they are not really as good, collectible, or as valuable as the Kodiak series of bows with the clamp down limbs, they are decent shooters.
Your best bet is to go to ebay and search out bows like yours in the "completed sales" catagory to see what they have been selling for. You did not say how much you paid, but this will tell you if you gat a good buy or not. Any bow, cheap or expensive, is worth what people are willing to pay for it. No more, no less. Bottm line is it does not matter how much you paid, if it is worth it to you, then you made a good buy.