Here is a link to look at www.cajuninjector.com
. They have several different brands/ideas to try, including a recipe section. Another link is www.barbecuen.com
. Go to the recipe link for a lot of ideas.
I have used a Creole Butter Recipe from Chef Williams' (store bought) that is pretty good.
I guess the best thing to do is experiment to develop something to your taste, and make it fluid enough so that it can pass through the injector. Also, put the amount of marinade that you will be using in a separate container so as not to contaminate the entire jar.
There are a lot of good ideas here. The best thing to do is search the site. Good Luck..