That was my instinctive reaction as well: money is more for hiring help or buying equipment now. Most of my "professional development" now starts with online sources, including tutorial/reference information about different technologies and discussions with other developers, and most of that is freely available.

In my earlier years as a developer I also bought a lot of books and some of them were very useful, and from time to time I still find a good one. If I were at the same stage today, I'd probably also consider online training courses, as some of them do look well presented and for getting up to speed quickly in a new area that sort of guided material can be helpful. (The same applies to in-real-life small group training courses, when that sort of thing becomes more practical again.)

I'm not a big fan of convention/lecture formats, though. They tend to charge a lot for admission, and IME they are rarely worth the time and money, particularly because these days you can often find much of the best material from any particularly good presenters available freely from other sources anyway.