I will be buying a new ballast and light set soon. My garden has outgrown my 430 watt hydrofarm HPS system (cant complain though its a good system for a small garden). I'm looking at getting a 600 watt system to run along side with it. What are the main differences between the magnetic and digital ballasts? Is one more reliable than the other? A brief scan through amazon and I see several ballasts in the $100-$150 range and then others in the $200-$250 range. I assume like everything else in life you get what you pay for...are there any systems made in the USA as I wouldn't mind spending extra to keep my neighbors employed.