Bar H.....There are a couple of ways to buy the Silverleaf system. If you buy one of their boxes, they're VERY expensive. A lot of people just use a laptop or tablet and buy the cable. The Silverlea VMSpc program is free. You can download it to any computer and actually configure it the way you want ie: analog gauges, digital gauges or bar graphs.
If you decide to use your own computer, you can shop prices from a couple of RV vendors for the cable. The cable is about $300.00. Here is a vendor
SilverleafHere is a photo of mine.