I just read about Crossover Office, and am curious as to whether it makes sense to pay for it. Apparently it's run on Wine, so aside from the support options, what features does it have that I can't already get by running a program with wine? (Or in other words: is it worth paying for?)
Original answer: The main thing you get for paying for this software is support. Commercial software has better support because of course, you paid, so they have to give you something worth paying for, so to speak. Just a note though, it is not run on wine, but rather based on WINE, and developed from the same code, with some additions and gui features to make it easier for inexperienced/casual users to install software on WINE with it. You could of course do quite fine without it (I do), or you may require it for the greater support it offers (this depends on your skill level etc). One more thing, paying for such a product as CrossOver Office will support the development of WINE, so it is one of those things where even though you don't have to do it, you do it cause it's for a good purpose =).
Updated answer: Is it worth paying for? Yes, and no. If I'm very honest here, it is worth it if you want to help the development of WINE, and it is worth it if you need the support. Yet, (see below) there are alternatives, as always.
In response to your comment: You can try various tools for running applications that don't run well out of the box with WINE, for free. The best in my personal opinion (and most maintained) is PlayOnLinux.
PlayOnLinux main window.
PlayOnLinux install window.
You will find a pretty simple gui for installing many different applications on wine (mostly games, unfortunately). If you can't find an application in that list, then you can check the playonlinux forum, and see if there is a script download for it. If you need further, direct assistance, there are several places you can go, including winehq, where you will find a good support forum, ubuntuforums.org, or even here, AskUbuntu.