If you go to Letraset's( Promarkers makers) site,
HERE , you will find all the different packs shown, and when you click on each one it will tell you what colours are in each pack. They have all the different pack sizes & types here. Also you can download a colour chart, or a chart you can colour in yourself. I found this 'cos like you, I didn't want to buy a pack to find I already had half the colours, and there are some colours which are in more than one pack, which I think is a little naughty!HTH