I get the feeling they send plenty but the people aren't allowed to say when they've got one. The testers could be anyone or anywhere. In our threads, liking our posts. Like mini more silent versions of the Devs.
"Ladyinsanity likes this"
Senpai noticed me. 
Well, damn. I know I've should of gotten one by now. I signed up pretty early.
I'm afraid that's not how it works. I think it was the keep thread (or maybe on twitter) where they said they're sending out the e-mails based on the types of players they need. So, you can imagine something like, Group A - Experienced Dragon Age Players, Group B - Never Played Before, Group C - Exclusively played DA2, etc.
They need a wide variety of players to test. I'm not saying put your hopes down, but not getting an invite if you're an experienced player is probably quite a strong reality, as most of the people who signed up will be.
sorry! please don't shoot the messenger, i just don't want people getting their hopes up and being crushed.