Patching a pond liner—especially a cheap one—is a lot harder than patching an innertube. First, there's the pond itself. A liner needs to be dry for adhesive patches to adhere, so you'll need to drain your pond at least part way, and that often means relocating your fish and some plants to give you room to work.
Adhesive patches require cleaning, drying, priming, removing air bubbles, sealing, and curing (usually 24 hours) before the water and fish can be returned to the pond. It's a big project even for a tiny hole, and even a tiny imperfection will bring a new leak. Paying more for a durable reinforced liner from the start will save you a lot of time, not to mention heartache.
