aflop

It sounds like it could work both ways. But honestly i think if your contractor is careful enough he should be able to avoid damaging your floor tiles. However, from the rough hacking and vibrations from the power jack, hairline cracks may appear on the tiles closer to the walls. Just my opinion.

Honestly i don't think there's much you can do about it. You can try, but it may be futile. I guess the prices for electronics will keep depreciating over time so you would expect lower prices (albeit not that quickly) as time goes by. That's why i always use stores like Gain City/Audio House/Mega Discount store that have lowerst price garantees. I've managed to claim back a few hundred bucks difference on my TV when i spotted another place selling cheaper.