If they really believe in what they're doing, they won't want to give chunks of it away so cheaply. Conversely, if they're willing to sell on those terms, wouldn't you be concerned that they aren't serious?
If they're college kids or new college hires, you'd probably banking on them not knowing how valuable whatever they're making is.
Angel Investors get huge stakes for their small high-risk outlays.
http://blog.ycombinator.com/the-new-deal/
> We have a new standard deal at YC—we’ll invest $120k for 7%.
> This replaces our previous standard deal of on average $17k for 7%, plus a SAFE that converted at the terms of the next money raised for another $80k.
Originally, before they invented the SAFE, there was no SAFE in the deal