Are your Full Details simply a wash and wax and interior cleaning? Typically that term refers to additional services like paint cleaning, IFO removal, and swirl removal. If you have customers that have been shopping around or using other detailers (as it sounds like they do) then they may have certian expectations when you use terms like this.
There isn't anything wrong with undercutting everybody to this degree. However, if you want to get serious about detailing then you have come to the right place. The first thing you need to get is a PC. Then you need to start getting practice on how to use it for swirl removal, paint cleaning, and waxing. You will save a ton of time and I'll bet it won't be long before you realize you are charging half of what you should be charging. You are in a good area to get good detailing supplies. Premium Auto Care and Autogeek are in your neck of the woods. Definitely do some research and you'll realize that there is a lot more you could be doing to really make some money at this business.
Is this your full time job or just a side deal?