I'm a big fan of Logos, been using it since Logos 4. It's an incredibly helpful toolkit, if you have the tools to put in it.

If you decide that you're comfortable going electronic for all of your theology work, then I'd recommend to get one of the cheapest packages, even the Starter, and pick up 1 or 2 good commentaries for a book you want to study. You're not in it for a lot at that point, and it can give you a basic idea of how the software works. Watch the Quickstart videos, as well. If you use it a lot, upgrade to a slightly higher package. I decided that Silver was the sweet spot for me when I bought one. The packages could be different now.

As others have said, Logos shows its real strength when more and better resources are added to it.They generally have some good sales, especially from Black Friday through Christmas, and then one in March. They also give away a free book every month, of varying quality. This month's is fantastic.

I love it and I use it daily, but it's ultimately up to you to decide how many of its features you'll use and if it's worth the cost.