For that money you can get IBM datapower. Which is an all in one very powerful solution... With near wire speed transfer. I don't know why I should get that?
I am pretty sure that it's a kind of good option for some enterprises. But most of our customer has high volume applications deployed in several datacenters, with CI/CD and DevOps approaches used. For them, hardware security boxes are almost impossible to use. What they are looking for is DevOps friendly tools that scale and orchestrated well with their application. That is why we're partners with NGINX to provide all the flexibility of our filter nodes.
Moreover, IBM thing will not help you to figure out security flaws in your apps and network perimeter. It will not provide you with details which of millions of malicious request you really need to care about as they are targeting existing security flaws.
I would like to get your feedback about this IBM product. Do you use for some time? It's not that popular among security community (at least, that part we usually talk with). If you give you access to test it, we'll show you some bypasses — unfortunately, there are dozens of them for almost all old-fashioned security solutions like this.