When a domain expires it shows in the whois for a few weeks before any one else can register it. There are places where you can browse lists of these expiring domains and if the domain is worth anything people will race to register it first. To win these races people use a register that does backordering to register it within seconds(not 48 hours) of the domain being available.<p>If the domain is worth registering it will be available and registered by someone else before your system even knows it was free.<p>Your pricing is also way off. Godaddy will poll at least every minute until they get the domain for a flat $20. You are charing $200 to poll once ever 12 hours for a year, doesn't even include the cost of the domain. If the domain is worth $200 some one else will have it sitting on backorder and you will never get it.<p>iirc sedo was the fastest at backordering but more expensive that godaddy, I guess you could charge $200 a year and if its a godaddy domain use godaddys backorder pocked the $180 extra if its not backorder on sedo and provide a better service for the same price.
Btw. gmail shows me this when i click the "Login now" link: <a href="https://vgy.me/QNXHml.png" rel="nofollow">https://vgy.me/QNXHml.png</a> . I don't know why it considers your site to be "untrusted" (whatever it means), but it might be worth finding out and fixing, so it doesn't drive people away.