It depends on what you're looking for. If you want a "home", then you're probably looking at a 'Sprinter' style van. I've seen them complete with a shower and toilet; but they cost a pretty penny. The more amenities you take out, the more affordable it would be.
I agree, if you are trying to do it yourself, definitely consider having a professional do electrical, especially if adding solar panels. Also depends on where you live. If you need to be able to live in it in the winter, then like a RV it will need to be "winterized".