lawyer cost for startup documentation

Shop around -- if you can split the bureaucratic job into small easy pieces costs usually drop substantially. There are plenty of documents you can download a template for free or for US$5-10. Call me if you prefer talking to writing.

It really depends on how "huge" the money is, how the deal is being structured, and what kinds of documentation the angel is demanding.

If this is a Series A-type investment of multiple millions of dollars, then $10K isn't crazy. Those rounds usually involve a lot of paper, unfortunately: a whole set of interrelated contracts, amending the corporate charter, etc.

If it's a $10K or $100K investment, though, then you may be better off with a simpler deal structure, perhaps convertible debt. Take a look at the Series Seed documents (http://www.seriesseed.com/) for an idea of what a simpler deal can look like. One of those can be put together for $5K or less.

If you haven't actually incorporated, then you'd need to do that too (first).