I think the concept is great! If his market can sustain his business, then he must be doing something right. Just because his prices may not be in line with other areas of the country doesn't mean that he is overcharging. There are plenty of people today who are willing to pay extra for things because they are "green"/environmentally friendly.
I would assume the "in conjunction with gas powered equipment" would be in reference to his gas powered smart car and the aerator that he uses. There are battery operated trimmers/blowers available, like the ones now available from Stihl. With the solar panels he has, I would assume he can charge a couple batteries at a time and has other batteries ready to go.
Now, I don't know how long the smart car will last seeing as it really isn't designed to tow trailers. Maybe the owner has "beefed up" the car somehow to help it handle the weight of the trailer and equipment. But yet, the weight of the trailer and equipment is probably quite minimal compared to what is usually seen in lawn care (i.e, the 18' trailers with ztr's and walkbehinds on them).
If you live in the right area of the country, I think a business like this can really succeed, especially with the importance placed on going green today. I don't think this business would survive in all areas of the country, but in some. I think its a great idea!
'07 Chevy 2500HD
2010 John Deere Z925A 54" MOD
2011 John Deere Quik Trak 647A
John Deere walkbehind