I have a couple of store bought animations, a rocking skeleton and one of those butler dudes with the spinning head.

I'm fond of stuff like that, they are affordable somewhat.

I've been very disappointed though because many of the newer props have only motion sensor activations, or sound activation.

I realize that some of these things have motors that couldn't hold up with continuous operation. 

My preference is continuous operation OR in the case of a high end animatronic, something that is activated with a heavy duty PIR or pressure pad.

Does anyone else feel like this or is it just me.  I would however go for a prop that had motion or activation at different intervals, that would be cool too. 

It depents on the prop. If it has a lot of sound  effects  than it's good that it's only motion/ sound activated. The only thing that sucks is that almost everything sets them off. But if the prop is one that is just doing a continuous motion like stirring a cauldron I would want to have one that just stays on.   

I have to agree with the stuff is not made to last.  Even the static props are being made cheap.  I have seen some very nice, well made props but the prices............OUCH!!  When your not making the money on your haunt to support the big purchases then you need to resort to making them yourself!  Well at least I try to!  LOL!! 

When it comes down to it a constantly moving prop is much better then a static one.  However, a prop that moves when you trigger it, I think is much better! 

I don't like keeping those cheaper animations running for long periods because they do die! Been there and done that. Maybe you could attach to a homemade motion detector.

I HEAR YOU,THOSE CHEAP ONES BREAK TO SOON,OR DIE ON THE NIGHT WHEN IT COUNTS THE MOST,OR THE SOUND GETS ALL DISTORTED,,THEN THERE JUST CRAPPY AND YOU HAVE TO TURN THEM OFF

AFTER A WHILE I JUST STARTED BUILDING MY OWN..UFFF

I like the challenge of building myself.  The more I do, the more I want to attempt. (My wife says I have OCD)  I enjoy the sense of satisfaction I get from coming up with something that is really cool and scary.  I've seen a few store boughts that I may purchase, but they have really awesome detail, way beyond what I feel comfortable attempting at this time.  I agree with hauntwizard, the really good ones are just too pricy for a small haunt.  I found one online, a huge giant, that I really liked.  It had motion, sound, and blew fog, but it costs like $30,000.00.  Way above my budget!!