Toilet repairability

Our old cheap toilet you can't get parts for anymore (dual flush). I remember my dad fixing old singl-flush toilets with just standard parts from the hardware store. But these new dual-flush toilets are super proprietary. Are single-flush toilets more standardized to where I would be able to easily find parts? I am thinking yes, but the plumbing parts store says otherwise. Am I missing something?

Edit: to clarify, my wife and I hate the dual flush so we're going to buy a new toilet. I'm more wondering if the NEW toilet will be easily repairable. Sounds like maybe the old one is more repairable than I thought, though.