Having one person isn't going to help much, even if they don't get replaced, it'll be a hung jury at best, unless they're the most persuasive, charismatic person on earth.
And you generally don't want a hung jury. It's just delaying, and now the other side knows your entire defence strategy and can prepare on better countering it. You having information on their strategy isn't as valuable.
I mean, there's a lot of things you can do for free that we pay people for. They've put together a device that is preloaded with a ton of information. To do this yourself would probably take most people a week or 2, at best a weekend if you worked hard and had pre-existing knowledge and a fast connection. Maybe longer depending how they modified the raspberry pi, though you don't necessarily need it to do everything they made it do.
You'd pay in this range for someone to clean your house for a few hours. You can also do that free. It's the convenience you're paying for.