Motor Size /Joystick Question

I have an project that uses bipolar stepper motors to pan and tilt a
metal table weighing about 20 to 30 pounds. The steppers are not
controlled using a PC, but by using a joystick. I know that an
oscillator circuit (555 type) can be built to run the stepper motor
drivers in 'standalone' mode, but ususally this involves using
external switches and doesn't provide variable speed control with a
joystick, which is what I want. As I move the joystick I would like
the speed to increase or decrease just as it would say in a normal PC
game.

I've spent a LOT of time searching on google and found a few
interesting things, the closest being this :

http://www.imshome.com/osc.html

which plugs into IMS's bipolar stepper motor driver.

Can anybody think of something cheaper/better ?

And now for another issue, I don't have much of a feel for how
powerful the bipolar motors need to be to pan/tilt the table. Lets say
for the sake of argument that the motors and the table were geared,
like 2 cogs on a bicycle with a chain, to provide more torque at lower
speed and that I wanted the table to be able to turn 180 degrees in
roughly 2 to 5 seconds. Noting the weight above (20 to 30 pounds) what
would you recommend for motor size (other than bigger is better :)

Thanks,
Matt