Hi.
if you want something just to play with then what you have linked to already will be fine.
If you want a stepper to actually do some work then buy a decent one to start with.
The determining parameter (after size and holding torque) is inductance, the smaller the better.
You may well find a powerful stepper, say 500 oz.in but 4mH. A less powerful 400 oz.in stepper but
much lower inductance 0.9mH will perform much better overall.
The lower the inductance of a stepper means it can run faster without losing steps, always the Achillies Heel
of any stepper.
The next issue is the driver. Go for a driver that has the highest voltage capability.
Gecko 213's have a great reputation for reliability and capable of 80V, they are somewhat more expensive but good quality.
Leadshine AM882 also have a good reputation, 80V up to 8.2A, in the region $65-$75 on EBay.
The higher the voltage allows a stepper to run faster, it counteracts the inductance.
Craig