More constructively, what are you trying to accomplish? There are few goals that a press release will help you with. It may help with some vanity links in Google News if you search for your name, but that's about it. If you want press coverage or user attention, a press release is almost certainly not going to help.
Ditto this. It's likely not to get you any press of value. Write some personalized, targeted emails (or get intros) to press instead. Tell a compelling story (tie into an existing narrative if you can) and keep it short and to the point.
The most clever press-releases I've seen in recent-months have taken the form of guest-articles / guest-posts on places like TechCrunch. Of course it can't be a hard sell (no overt plugs). But they can be an opportunity to demonstrate your knowledge of [insert-your-vertical] and come off as an expert in that field. Somewhere in the post the magazine will reference who you are and where you work, and that alone might do more benefit than any traditional PR syndication service would.
The question you want to be asking is "Who should I submit this to?", not 'Where?'. Which writers, bloggers, journalists etc have shown relevant interest to your startup's sector or pain point in the past? Write to these people individually, thanking them for having shown such an interest (link to a great article they've written, especially if you read and enjoyed it at the time) and introducing yourself, your startup, and the newsworthy angle you have decided for in your release.
Keep the email punchy. And if you do get any kind of response, even if it's to decline to write you up, be ever so grateful and make it clear that you would be happy to provide expert opinion on this topic if they ever sought it in the future.
And if you still don't believe us on press releases, read the article I wrote for the PRSA that questions the press release's value, and debunks that it will help with SEO or social: http://comprehension.prsa.org/?p=6202
I don't think either will be a catalyst for anything significant - there's just craploads released every day and it's unlikely anyone will notice yours unless you, your startup, or your investors are notable enough that journalists are specifically watching for them. It definitely won't be worth paying for.
Sadly the only thing submitting a press releases did for me is to ensure that I get weekly spam from press release companies, and individuals willing to fix my SEO and boost my sales.
More constructively, what are you trying to accomplish? There are few goals that a press release will help you with. It may help with some vanity links in Google News if you search for your name, but that's about it. If you want press coverage or user attention, a press release is almost certainly not going to help.