One of my favourite bathing suit pioneers is Black Milk Clothing. Unfortunately their prices are a little out of my budget but they have some of the most creative, pop cultured inspired designs.
Another great website is ModCloth which showcases an extremely adorable selection of vintage clothing (thus the outrageous prices). Although the prices may seem a little bit intimidating you can always get lucky and find some just as appealing things in their sale category.
ASOS is a more reasonably priced place to find a vast selection. It's a great way to mix and match so you don't have to fish out 40$ on one bathing suit you're forced to wear all summer. They have a huge variety of colors and patterns including some in that retro style.
The cheapest alternative I have found so far is from Forever 21. Most of their collection follows a similar patter of neon colors in that tradition bikini shape. Not particularly my choice but I thought I'd share them anyways because of it's extremely cheap price. I guess it's something I could learn to love for only 6$ a piece.

























