I just started to build one myself to get my feet wet. I currently have two WiFi power plugs, an Amazon Echo Dot, and a Broadlink RM Mini 3 (IR blaster).

Got most of it working, including remotely controlling the TV, A/C, two bedside lamps (using the powerplugs) from my mobile phone. All but the A/C works with Alexa and I'm still figuring it out with the developer.

In the future, I might get either a Broadlink RM Pro (supports both IR and RF control) or a Logitech Harmony Hub, more WiFi powerplugs, and WiFi smart light switches to replace the current mechanical ones.