No, the next limit after 50 is 200, then 350, then 500.
Heheh. dave741, you beat me too it - I started a response an hour ago, then had to go to a meeting before I finished. ;)
In that response, I wanted to point to this page from the AdWords Help Center, for additional details:
When do you bill (for post-pay advertisers)?
[adwords.google.com...]
Excerpting from the above Help Center page:
...Your credit limit is raised in increments each time your account hits its credit limit before 30 days have ended. The initial credit limit of US$50 is first raised to US$200, then to US$350, and then to the final limit of US$500. Each time you reach your credit limit or after 30 days, a new billing cycle begins.
AWA
If I weren't such a lazy bum, I probably would have found that excerpt in the Adwords content pages!
