It doesn't matter how much the aiming system and the laser costs, that's no reason to destroy VALUABLE, perfectly new and workable equipment. They could just as well have aimed the damn thing at a barge loaded with rubbish.
Idiot reasoning like yours is to a large part reason why we have such a shitty civilization on this planet.
The outboard motors could very well have been cast out of solid silver and still been cheap compared to the laser and the aiming system, is that a reason to sink a quarter ton of precious metal to the bottom of the ocean? No, of course not.
Dumping relative pricing comparisons where they belong - on the shitheap - in absolute terms 2x200HP outboarders are fucking expensive, they're gotta be worth ~$25k, maybe more. There's no sane, credible reason whatsoever to destroy them just to test a very very very very expensive laser.
How much useful stuff can you do for $25k? Quite a bit if you think about it.