With regards to the service you are providing I think it’s one of the closest offerings to my guide in doing the filtering for domains.
However, I'm not here to talk about the guide I'm here to answer some of your questions.
First of all, it does add some value to GoDaddy Auctions to the normal user but there are some features missing which would improve the usability and functionality of the service.
Whilst the usability of it is 'OK' although when you compare it to other domain services it’s actually a LOT better than others - there’s a few features such as 'price', ability to filter domain extension, remove hyphens etc that need to be added and also the 200 limit isn't as much as when I'm using GoDaddy Auctions, I'm always selecting the 500 option (and then I still think 500 is too limiting!)
There are other types of auctions on GoDaddy Auctions - a lot of trades happen around "buy it now" and a few other options which your service doesn't seem to pull them - you really should.
I'm not sure about the issues with regards to GoDaddy itself as they own gomommy.com (which redirects to GoDaddy) and I'm not sure if they hold a trademark on "GoMommy" but you should definitely look into it from a trademark perspective.
With regards to monetization of the service, there are a few ways you could do it - one way is via a fee - although $10/month is a little high for it as it currently stands and you also need to compare this to TDNam (GoDaddy Auctions) that the price point is only $5/year.
If you are looking to charge for the service, then you definitely should add a lot more features to the service (including some of the ones I listed above).
However, there’s also incorporating GoDaddy's Affiliate Programme into the service - so that whenever anyone buys the domain, you get a % of the sale. This wouldn't even be hard to incorporate as they already get to the auction clicking the link anyway so it’s just slightly modifying the links to incorporate your affiliate code.
Additionally, you could also offer a 'free' and 'paid' services - the 'free' being the one currently as it stands (although I would still add some features) which incorporates the affiliate option and the 'paid' having a lot more features whilst still incorporating the affiliate links.