AWS is definitely aware that their costs can be prohibitive for brand new startups. Check out AWS Activate[1]. If you can demonstrate that you're a legit startup, there's a decent chance you can get free AWS credits, not to mention free support.
Getting the business level support is absolutely necessary if you don't have someone with AWS experience and are doing anything substantially complicated. The free-ish support is, on the whole, pretty abysmal. The availability of solution architect time is not always useful. You ask 3 people and get 3 different answers. I've given some thought to doing consulting around this for equity but haven't figured what that would have to look like. There's a lot of wrong turns one can go down pretty easily. Bottomline, Activate is helpful but not sufficient.
[1] http://aws.amazon.com/activate/