Its not too hard to get into the goldbox:
1. clear your recommended items
2. go to one of the "other users who bought this also bought" items
3. click i own it
4. go back and clear your recommendations again, except the one you want to buy -- leaving you just the item you want in your recommendations
5. wait. (i don't know how long; sometimes its instantly, other times it takes up to 24 hours)
6. it will now be in the goldbox