It was the brick base of the water tank, so it bounced like a wall, but because it was curved, the ball would sometimes move away. In general some kind of ball against a wall or tee-ball game is handy enough for what it is, but ultimately the flight of the ball isn't helpful.
Supposing you get a willing partner, there is always a fundamental problem. Bowling is more exhaustive than batting and it's hard to do accurately. Thus, man created the throw down. However, throw downs will still wear you out. So ideally, you only do a big set of throw downs with a throwing aid. The Sidearm is the premier product for accurate, fast and easy throws, not a bad price at around $50 and a lot of clubs have them because they do work. On the other hand, if you're cheap, try a dog ball thrower for around $10.
At the high end you can actually get small bowling machines now. The Paceman is about $350 and bowls at up to 90 kph. Granted, it's not as impressive a machine as say, Merlyn, but if you're intent on filling your free time with net sessions, the price is no less plausible than buying something like an XBox.
Also, that cricketcoach app is pretty cool.