Wedding favours should be fun and inexpensive since it is the thought that counts. One thing, however: make sure that whatever you give out will be appreciated from all the people that attend your wedding. I say that because most couples tend to give out only one gift. That gift might not be appreciated to the same extent depending on whether you are male, female, young, or old.
That being said, there are many ways to come up with ideas as to what to gift. If you are inviting people from abroad, you might want to give something that reflects the local culture. Alternatively, if you decide to hold your wedding during a special holiday (i.e., Christmas), you might want to add a Christmassy touch to your wedding favours.
In such ocassions, if you’re making your own wedding favours, the materials to make them could be easier found (i.e., gold and red cellophane wrapping paper are usually only available during Christmas) and could be cheaper (since there are more suppliers offering the same thing).
On a last note, while most of the wedding is about you, wedding favours should be about the guests. Or, in other words, you should give something they will want to keep and something that has meaning.