Yeah, I installed a few in my garage this past fall. Still got 1 more to go when the youngest one gets a bike. They seem to work pretty good. Most places I've seen them are usually $30-40. I just saw them on sale at Menards last week for $20. I've never seen them for $15, I'll have to check Target next time. I've even seen them at bike shops for $80, and I'm sure those are probably better quality, but these cheap ones I have seem to work fine for me.
They seem fairly safe too. You have to pull the rope to a certain angle, and let it out slowly, to let the bike down. If you let go of the rope, the bike will not fall. I'm sure accidents can still happen. I would never park an expensive car that I really care about under these, but for my daily drivers I think they're safe enough for me to risk it. Personally, I'm more worried about them falling on my kids, so if my '99 Tahoe is parked under the bikes, at least I know they aren't going to fall on someone.