Truthfully I'm fairly certain that the relatively small 'company' behind Dependico is just one lady (I think her name was Monika..?) doing something she enjoys/has a passion for. So I'd think the odds of finding a coupon would be somewhat limited.
Because of the size of the operation, I would think you would have better luck simply emailing the owner directly potentially seeing if you can work something out with her personally.
That being said I would think paying full price for one of her products still a good option even if it might seem a little bit pricey. She does a fine job and there aren't many out there are going to make products like those that she does. Buying her stuff is actually supporting her in a very direct way.