If you are looking for affordable smart switches, the Tuya devices are very affordable alternative and the can integrate with your openHAB instance.
How do I connect tuya smart plugs to openhab? - Beginners - openHAB Community
Complete Guide Connect Tuya Plug To OpenHAB and Home Assistant Using Tasmota
How to Connect openHAB and Tuya Devices - The Smart Home Blog
Tuya LOCAL with energy monitoring and without tuya-convert - Configuration - Home Assistant Community
Linking Tuya Smart devices - Bindings - openHAB Community
How to Connect openHAB and Tuya Devices - The Smart Home Blog
Flashing any Smart bulb, plug or switch with Tuya-Convert
Smarthome/J Tuya Binding support for WIFI TUYA Energy Meter 63A with voltage current and leakage protection (Need HELP) - Bindings - openHAB Community
How do I connect tuya smart plugs to openhab? - Beginners - openHAB Community
Home Assistant Ecosystem