When a user wants to create and/or edit PDFs, there are several options. This post will lay out the most common ones I have come across, including costs as of 8/6/10.
Office 2007/2010 - You're able to create PDFs from any of the Office 2007/2010 programs. From Word, Excel, PowerPoint, you can choose Save As and save any file as a PDF (you'll need service pack 2 or the PDF add-on to be able to save in Office 2007).
PDF995 - a low cost option for creating and making minor edits to PDFs. From PDF995.com, one can install the PDF Suite, which includes PDF converter and PDF editor. The PDF converter will let you create PDFs from any program and the PDF editor will let you make certain edits within an existing PDF (add page numbers, extract, remove, combine pages, etc). PDF995 is free as an ad-supported version (you see ads as you use it) or you can pay $19.95 for the PDF Suite or $9.95 for the PDF converter only. PDF995 is cheap, but not as full featured or easy to use as the more expensive programs (see below).
Adobe Acrobat Standard or Professional - Often, Adobe Acrobat is considered the gold standard for PDF creation. Adobe Acrobat Reader (which can only view PDFs) is far and away the most common PDF viewer. Adobe Acrobat Standard allows for PDF creation and editing in most ways. Acrobat Professional also adds functionality for protecting PDFs and creating forms. As of 8/6/10, the MSRP of Acrobat Standard is $299 and the MSRP of Acrobat Professional is $499. Often, you can save up to 30% from online stores like Amazon.com.
NitroPDF - NitroPDF is a full featured alternative to Acrobat Standard. As far as I know, it has all the same functionality as Acrobat Standard. As of 8/6/10, NitroPDF is $99. I have several clients using NitroPDF who have used Acrobat and find it just as good (or even better) for significantly less money.
For basic PDF creation, often Office 2007/2010 is plenty for most users as most PDFs are created out of Word or Excel. For most advanced users, the PDF995 Suite is generally good enough for basic uses, but I find most average users have some trouble with the interface. For the average user, I recommend NitroPDF. It's more cost effective than Acrobat, and it's a solid program. For the most discriminating users, I recommend Acrobat Professional.