Showpo has a standard promo offering 25% off jewellery with the purchase of a clothing item, which can effectively get you 50% off the market price on some styles.
I saw a simple navy colour dress with the lace detail at the bottom, which fits most figures and is available in all sizes from 6 through 12 for $50. The average price of a casual dress over at Beginning Boutique is $69, but as in most cases I couldn't find a similar dress due to Showpo's unique style.
What's more of a bargain though is that you can get a matching piece of jewellery at 25% off - this is a Showpo promo available at all times. I find that the Asgard necklace goes pretty well in combination with this dress, adding it to your cart will cost you an extra $21 (discount is automatically applied at checkout). Looking around at ASOS and Beginning Boutique, similar style necklaces start at $39 and go all the way up to $70, which means you can save 50% on the market price of this piece of jewellery.