We're moving to AWS for our next release, managed by Rackspace. Had the same philosophy as you for years, and have saved a lot of money with DIY (maybe in the tens of thousands).

Turns out server admin is not my skillset, and it's caused problems, headaches and risks in the past.

I consider the additional cost going forwards in effect as our next hire and an important one. For small startups looking to save money DIY can be a good option, but moving onto the cloud at a later date can be a big burden.