'Kingly Pet' - why are you so concerned with markup/profit of companies you would wish to sell to ?
Should you be only concerned with your own profit/markup ?
Do you manufacture your own product - or - do you on-sell ?
Do you know what your costs are - variable and fixed ? You will need to know these before you can put a proper/adequate sale price on your product.
The sort of question that you have asked here - maybe - how long is a piece of string ? - would answer it for you.
Here are some links from the ATO - regarding benchmarking. Take note - the figures are only worked on averages - so maybe no help - but maybe will give you an idea of profit margins that the ATO are using to audit companies. Depending on how companies and other retailers are structured - will depend on their financial results.
Small business benchmarks | Australian Taxation Office
Benchmarks A-Z | Australian Taxation Office
Pets and pet supply retailing - issued 2012 | Australian Taxation Office
Veterinary services - issued 2012 | Australian Taxation Office
I am aware that I haven't answered your specific question - but I have asked you some questions for you to think about!