Go on the internet and shop until you drop. Google a few different combinations - with part number, without part number, with product name, without, etc. Different vendors can pop up. Went looking for a Reese DC WDH last year and shopped all over the place. The best price I could find anywhere, including shipping, was ebay. By about 10% IIRC. The only caution I would have is ensuring you have a full warranty, is easily returnable and is likely to help if there's an issue (missing or broken part, ex.). The only place I've had a return issue with is Amazon. I've even offered a few ebay sellers a bit less than what their item was listed for and got a discount. This can work with vendors that also have a regular online store.
Gil & Deb & Dougal the Springer Spaniel
2014 KZ Spree 262RKS & Ford F250 supercab V10 4x4 LB