I discussed some practical issues with the iText AGPL license in my blog (which is linked from my SO profile). Why not just buy IText? It is certainly an option among many commercial PDF libraries out there, although they really need to standardize their pricing against the competition.
The truth is I never really used iText much in the past. It always either lacked certain features, or the API was much more difficult than other (non-free) alternatives to wrap your head around, especially for minimal PDF manipulation (rather than the level of PDF manipulation required to generate a report, for example).
At this point the only similarly licenced PDF library I know of is ICEPdf, which is under the MPL 1.1 license, but its business model is to have a more limited version and charge for more advanced features (such as more font support).