Some quick points from me, for what they're worth!
- You could do with improving your design skills somehow. This is pot calling the kettle black, as I don't do much high design at the moment, but the "feel" of the site is not good enough yet. Header design not good enough yet, colour scheme is a bit dodgy, really don't like the gradient backgrounds. I'm sorry if this is harsh, but design really counts. Maybe hire a good designer if you're serious.
- Need to work on conversion optimisation. Positioning of search box, put it in centre of page, then use marketing text to lead people into it. Look into conversion rate optimisation / landing page optimisation to get some ideas.
- The actual search box produces some really nice results, you just need to get people to use it.
- Publicity and marketing. If you really want to start making sales, you need to work out how to get PR. I need to do this too, which is why I keep telling people. I am going to start soon. You need to market articles to top PR sites and then you'll get links from major sites. Try and think of novel article ideas, e.g. The most luxurious motorhomes money can buy or perhaps "stars and their motorhomes", article about celebrities and their use of motorhomes when on set. Once the links come, you get the SERPs, then you make the sales.
- Trust and Confidence. I only use sites that I trust. If you want people to trust you, you have to tell them who you are. That normally means introducing yourself or at least the company, and having a phone number and address. This aspect is pretty important in helping to get people to use the site. Again, this is something I don't like doing, but I'm thinking of changing to improve sales.
- Last thing, a good publicity photo, e.g. really nice picture of motorhome somewhere, with your branding on the side, will work wonders and help with press releases.
Hope that helps.
Rgds