If you really want all heroes there should be something like this in shops:
http://www.gram.pl/upl/artykul/120081024153208.jpg
It has all heroes from I to V with all exp.
But still trust me everything you need is the King! Go buy homm3.
Later you may try homm5 maybe you will taste in it :/.
Edit: oh my memory just bring back additional complaint so i upgrade my first post
.