Unbounce's free service is pretty good, and it's what I've used, but you say it's not for you.
It sounds like you need to create landing pages repeatedly, and you don't want to pay recurring fees, so why not get some landing page templates from ThemeForest or somewhere, and use it on your websites with your styling? I guess it'd take some work, but you could make them customizable for your needs.
I want to optimize landing pages by continuously performing A/B tests through Visual Website Optimizer, which already allows easy editing of the web design.
I'll look into the themes from Themeforest but I just thought there'd be an easier way (DIY perhaps) to create an appropriately themed landing page.
It sounds like you need to create landing pages repeatedly, and you don't want to pay recurring fees, so why not get some landing page templates from ThemeForest or somewhere, and use it on your websites with your styling? I guess it'd take some work, but you could make them customizable for your needs.