Heard about MTrade through a friend and decided to give it a try since I needed to buy decorations and supplies for a baby shower. They have a good range of items for pretty much any type of party! Prices are average (i.e., 8 party cups for $5).
The only issue I have with MTrade is that shipping is $20 for orders below $150 which I find quite high. Self-collection is free but the shop is pretty far away.