Pumps are quite a discussion. My uro prescribed my Timm erectaid as "durable medical equipment". My insurance would not pay directly, but at least it would count against out-of network deductible. So I followed all the rules, and had them tell me where to buy it as an "approved" vendor. None of the approved local vendors who were shown as providers would carry a pump (comments from "inappropriate" to "porno shop junk"), so the insurance company was caught in a coverage issue. In the end, they covered it ordered directly from the factory under in-network, so it cost me what was left on my (ultra-high) deductible. I still had to pay up-front out of pocket, but I was reimbursed after about
90 days. Blew out my out-of pocket that year, so it was a wash in the end.
The difference from the ebay pump is that it has a long-term warranty, and as a prescribed item, if you have the amounts of expenses needed, it counts toward deductible medical.
All that said, if it is a cash issue, go over to franktalk.org and see what they have to say about the simple versions. If you can't go the $500 version, you would better try the lowest end devices, and $100 is a lot to pay in that arena.
Be sure that if you are paying much more than $100, the expense is at least deductible (i.e. Rx quality with a prescription).
Also, did you interrograte the insurance company about what they would cover? They may cover just one version, and not be allowed to discuss it.
I'm not familiar with the device you mention, but know too much about the denial process.