Just got a new 67 Gallon terrarium for the little guy and followed the guide above for a ballast for my 24" reptisun 10.0 T8 bulb.
I did this because the 30" Reptisun Terrarium hood from PetSmart was $70 in the store. That's significant savings when I paid around $20 for the ballast and wiring. Took about 15 minutes to setup and works like a charm.
Now here are the issues,
What I believe to be true about Magnetic Ballasts,
1. These cheap ballasts are magnetic.
2. They are not energy efficient.
3. They make noises.
4. They supposedly wear and tear on the bulbs and the UVB output faster.
5. They can cause the bulb to flicker
5. They are cheaper than electronic
What I believe to be true about Electronic Ballasts,
1. They are more expensive than magnetic
2. They are more energy efficient
3. They do not flicker the bulb
4. They will save the life of the bulb and make it's UVB output last longer
5. They do not make the humming noise!
I think all T5 ballasts are electronic. I like the T5 much better for many reason but anyway.
I think you'll find most people use magnetic ballasts because they are cheep. The most common advice is to use a cheep under-cabinet fixture from walmart or such, stick it to the wall and call it good. There are many reasons that this isn't great advice, but you can't beat the price. =\
Also, an engineered reflector will usually serve much better than anything out of cardboard and foil tape. But again, cost.