I'm sorry to break it to you, but you are not going to find a DP44 anywhere, including Ebay at this time. They haven't been released as far as I know.
What you are seeing on Ebay are SW44 switches. They are all Legacy equipment. They will NOT work with the new DISH PRO PLUS combiners that should be available in the second quarter of this year to combine the signal for two tuners onto one cable.
The difference is the DP44 is Dish PRO PLUS technology.
Would you like to buy one wholesale? The wholesale price is somewhere around $100. Then, of course, you have to add on the cost of shipping from the warehouse to the retailer, so really it's closer to the $110-120 range.