People buy stick homes all of the time and redo the interior to their own tastes. I'm not saying it would be cheap but it is entirely possible to paint the cabinets in any RV white, which is the latest hot trend. It is also possible to change the flooring to any color that you want as well as changing the countertops. Obviously the furniture can be reupholstered as well.
If you can do some of the work, this will keep the cost down but if you have to pay someone to do all of the work, the cost can escalate.
I would avoid an RV shop and stick with local shops to remodel the interior to your own likes.
If this is what you want, and have the funds to pay for it, just find the floor plan that suits your needs and go for it.