brisbane designer raking in millions on the back of hollywood 's blockbuster moving ` the avengers : age of ultron '
release of their new line caused the website to crash .
some items sold out in minutes when launched this week .
most expensive items are thor and iron man dresses at $ 100 .
swimwear is among the cheapest to buy at $ 45 .
fans of the series are buying up big because ` they are hoping to wear the outfits at early screenings of the movie '