Originally I had a plan to use relays to control the power to the various solenoids and coils, but as I found out, relays for +48VDC aren't exactly cheap. Something like 60$... and I need around 10 of them. Yikes!
After doing a little research I learned about the MOSFET transistors IRF640 which are ideal for this. They act like a relay but costs around 4$ each instead! A much more comfortable pricerange...
The best thing is that I can control the IRF640 directly from my Arduino board, since the requirements for "flipping the switch" are very low. There are also smaller versions available for even less which I'll probably be using in case I need higher powered lights than my Arduino board can power on its own.
A big thanks to Benjamin Heckendorn at benheck.com for helping a poor soul out regarding the MOSFET's. In fact - his Bill Paxton pinball machine was and still is an inspiration to my project - Great stuff!