While shopping for a mixed signal oscilloscope I had to wonder if it was really worth it to spend $400 for it. The reality is that it took me some work to decide if it was or not. I see that there are several models that you can buy for about $800. I took a look at the models that went for half that and found that they had all the features needed. These used to be relatively difficult to buy as most manufacturers were not issuing mixed-signal models. Today things are different. It makes what was once a niche market a little wider so these models are much more within reach and more feature-rich.
You can use this type of model as a scope alone which is useful. The sample rate is good, too. There are more channels, too.
While it is possible to get what is needed from a logic analyzer, I’d say the oscilloscopes are definitely worth the investment, especially if you buy within the lower price range. If you find this price range is not right for the needs you have, you can always upgrade to a more expensive model.