1973 Duster manual steering box

I am in need of a manual steering box for my 1973 duster. I looked online and found a few places that listed them for about $235-$245 but they were all discount type online auto part stores with no brand name listed. I did find a Jim's Auto Parts that had it but it was about double the price. I just bought this car and I am not that familiar with where is the best place to buy parts like this. Any help would be greatly appreciated. Thanks,

Jeremy