What is your preferred way to send a lot of email (newsletters, as well as transactional)?

Our volume is dozens of thousands of email per month. Up to 15k at once.

I need to make the right decision now and sincerely need your help; please pitch in with your experience with these or other solutions:

1. Pay for SendGrid or AuthSMTP to ensure deliverability. SendGrid has the additional benefit of built in analytics; for AuthSMTP I'd have to roll my own analytics. Both options are cheaper than Campaign Monitor (our current provider), but still relatively expensive in the long run -- we are a non-profit and function entirely off donations.

2. Pay for Google App Engine and roll my own analytics code. I have a lot of questions about this one. Is this the most cost effective solution in the long run? Is deliverability comparable to SendGrid/AuthSMTP for sending up to 15k emails at once? ie. Do the mail facilities in App Engine take care of SPF, domain keys, black lists, bounces?

I am _very_ cautious of having to write a mountain of new code for option two. Unfortunately, this is where it gets fuzzy for me. I've no experience writing analytics code (do you? headache?). Most importantly, I have no idea how much of the email plumbing I would have to do on App Engine. Please stop me if I'm biting off more than can be chewed by one person in a few weeks! Assume a no thrills solution: send to a list and track opens and clicks in the most trivial way possible -- no templates, segments, fancy UI or anything else.

Any other options out there?