How can I practice PLC programming without hardware?
Use software in place of the hardware. Write and run ladder logic in a free software PLC such as OpenPLC, then connect to the free LearnSCADA demo simulator, a live Modbus TCP water plant, and read it from your HMI or SCADA software. No account is needed.
PLC practice has two halves, and you can do both without buying a controller. The first is the logic itself: contacts, coils, timers, counters, and the habit of thinking in rungs. The second is everything around the PLC: reading its registers, wiring an HMI to it, and finding out why a value looks wrong.
For the logic, a software PLC does the job. OpenPLC runs the same IEC 61131-3 languages used on factory floors (ladder, structured text, function block diagram and sequential function charts). It runs on a PC or a Raspberry Pi, so a $35 board can become a real controller later.
For the plant, connect to the LearnSCADA demo simulator. It is a running process that speaks Modbus TCP, so you can point your own HMI or SCADA software at it (Ignition Maker Edition is free) and read its live registers as you would on a real job. The demo is shared, so it is read-only. When you want to start the pump and open the valves yourself, your own simulator dashboard is a private plant with writes allowed; a Free Reader account includes a 2-hour trial of it.
Together they give you the full loop: logic, a process that answers back, and a screen to run it from, with nothing on the bench but a laptop.