Hi,
Some know how of mechanical workings would be useful, if the targets are to just pop back up when hit then that makes life a lot easier - minimal programming (if any - I'll have to think) needed. How are your targets held in the down position? magnets?
A servo is basically a device that has a motor and some gears and other stuff inside which allows it to be controlled precisely (these are used in model planes,cars,boats etc) and can be rotated by the smallest fraction if need be. They are also strong for their size. Take a look at Marks youtube link, the servo is the small black thing with the white cross shaped plastic thingy on top, as you will see it rotates each way - once you have something that can do this then its "just" a matter of connecting it to your target via a linkage or whatever to make the target go up and down. The downside is, they need a controller, as in my earlier post, perhaps a model radio control unit although most of the cheapo ones are only 4 channel. It would be easy to take the transmitter apart and stick the "innards" in a box with some labels on 1-4.
I have taken a couple of pics of my setup which will hopefully explain things a little better.
Thinking about it now, my one if there is no magnet will pop back on its own (as in my crappy video where I hit it at an angle with the screwdriver) so thats actually that problem solved ! Just dont hold it down and it will come back up ! (but no delay) there has to be another (simple) way around this, maybe the motor with a cam on it idea would work, maybe continually rotating would do a better job than it just bouncing back as there could then be a bit of a delay in the target coming back up. I'll have a proper think about it tomorrow. There must be a simple that you can set something up without having to know allsorts of technobabble that you dont want to know !
The above is just my thoughts, I do have a habbit sometimes of overcomplicating things and hopefully someone can come up with something easy to set up, in the meantime I'll see if I cant think of something.
The £100 figure I guestimated was for all of them.
The 3 pics below are part of my prototype, they show the servo in different positions (target up and down) and the way I connected the servo to the target. The metal target when hit sticks to a magnet, the magnet is on a spring and another servo pushes this out of the way to release the magnet allowing the target to go back to its original upright position, I used a seperate servo for this as it seemed easier and more versatile than trying to get one servo to raise and lower the target without taking shock from the pellet (hope that makes sense!) The magnet can just be seen at the top right of the 2nd photo.
Hope that all makes sense !
servo with target in up position
servo in down position
servo linkage
[edit]
Theres a fair bit of DIY ish stuff on the photos, this is simply because it moves left to right, if it didnt then there would be much less "clutter"