Due to the rather niche nature of the HOOBS Starter Kit, and HomeKit in general, there isn't much in the way of competition. As far as actual hardware solutions go, there are only two similar options available: the Starling Home Hub, and the Home Assistant Blue.
The Starling Home Hub, while cheaper at $89, is rather limited in scope as it only works with Nest products like the Nest Thermostat, Nest Protect, and certain Nest cameras. Home Assistant Blue features a similar hub design as HOOBS, but it runs Home Assistant which is billed as more of a true home automation platform rather than just being limited to HomeKit.
The biggest competitor to HOOBS is the software that powers Homebridge and Home Assistant as both are available for free. By downloading and deploying a Homebridge or Home Assistant server on your own you get all of the benefits of HOOBS, without having to shell out any money if you have all the appropriate hardware and the know-how.
However, as I noted earlier, whether you purchase and install HOOBS plugins or roll-your-own server, you are introducing some potential security and privacy risks into your home.