Solution: Make the beta available to everyone BUT pump it full of ads. Like, ads everywhere. So, you fire your gun and it plays an ad as a sound. You also need to secure McDonald's or something., with Ronald McDonald yelling deals into your ear. Furthermore, all the aliens are tellitubbies where the TV screens show ads.
Ingenious, yes?
But, seriously, a sane amount of ads and beta availability to everyone could be very profitable.