Shed Alarm

So I have an observatory that can probably use an alarm shed, and I want an alarm that sounds on foot or alerts if someone inside. What is a good alarm that I can use that is pretty cheap.

Alex, there are several things you can do. Since protection of a home, you must make sure that you follow these tips against theft sealing a house, as they may apply to your return / observatory (such as not planting a jungle vegetation around your hangar to allow burglars to hide in):

http://yourhandymanzone.com/Your_Handyma ...

In addition to the foregoing, easily install an alarm system wireless security, as mentioned in this article:

http://yourhandymanzone.com/Your_Handyma ...

Good luck!

depending on how much your equipment is interesting, you may want to try someone like ADT or Brinks. others I have seen a el cheapo Radio Shack with a keyboard that you can install yourself.

Get a couple skunks plastic and put them near the shed .... I've never seen anyone who continues to go when they see one!
And no false alarm!
Cheap ...
and energy-star rated!