Pricing based on an hourly rate seems like the most logical way to do things. I will quote a job for my customers based on my hourly rate, and try to only give them a quote if I am able to inspect the vehicle first. If I am unable to inspect the vehicle, I will quote them a general range for the services they requested, and make sure it is completely clear that the quoted prices are subject to change once a thorough inspection of the vehicle can be done after it is washed.
I also agree with everyone that your website needs some changes. I use a company called Snap Pages to build my website. It is completely free (for the basic package), except for the purchasing of the domain name of course.
Feel free to check it out, I would highly recommend it since it has several templates for you to choose from that you can then alter to fit your needs. Yours appears to be a "home made" basic HTML site and is rather difficult to follow compared to many others I have seen.
You can see my site here, and can find more info on Snap Pages at hte top of the page:
Attention to Detailing - Premier Automotive Detailing Services
**Additional Edit: I also noticed, after taking a closer look at your site, that you list different descriptions for the same thing. IE: in one place you state that sealant will last 4-6 months and in another you state that it will last 5-8 months. I think you really need to take a good look at the entire site and consider doing a complete overhaul. You need a designated "home page" that states briefly who you are, what you do, and where you are. You need a "services" page that has a neat and organized description of the services you offer, you need a "Contact Us" type of page with a direct email box to promote potential customers to contact you immediately so they do not have to copy your email into their own email client, A photo gallery page is also recommended, and I've found that my customers enjoy when I do a full write up complete with before, during, and after photos so that they can truly see the transformation that their vehicle went through. I do this in a Blog Style format, and do not do it for every vehicle, but for the ones that I can tell will appreciate seeing the photos. The write ups are also a great way to show off what you can do and the passion you have for detailing to potential customers who are visiting your site.
Also, as you already know, referrals are one of the best ways to advertise your skills. Seek out local car enthusiasts by searching for Car Forums, Clubs, Owners Groups, etc that are in and around the St. Louis area. Offer a limited time deal to the first few customers, then post detailed write ups on their forums. I sponsor a local car forum, and in doing so, I get my own section on their site where I can post Write Ups, answer questions, etc etc and they provide me with a significant amount of business. I also offer a 10% discount to any of the forum members.
Business is out there, but I don't think lowering prices is the right way to go about getting it. Be creative, and get your name out there! I lived in West County (Chesterfield) my whole life (until recently - in Peoria, IL now for work) and there are exotic cars everywhere which means there are people who can throw around a lot of money! Educate people about how you can make their Porsche, Bentley, Mercedes, Ferrari, Lambo... you get the point... look better than their neighbors. Find some local car shows, and market yourself there. Car enthusiasts are everywhere, and chances are a good amount of them aren't aware that their paint looks like crap - find local car meet and greets, car shows, etc etc and market yourself. Make yourself THE PERSON to go to.
From a fellow St. Louisan, good luck!