Here is a list of my current trade lots.
Items with a (?) after the price means I am not 100% sure of the price and I am therefore willing to haggle.

Books
Alien Phone Book - 2mil

Trading Cards
Azul Swarm Trading Card - 2.5mil
Snoogle Trading Card - 1.5mil
Sultan Trading Card - 10mil

Gourmet Food
Chocolate Beach Cake - 3mil
Roasted Socks - 2.3mil
Vacation Gumball - 5mil

Potions
Purple Rusty Potion - 4mil

Costumes
British Costume - 1.5mil
Dark Fairy Costume - 9.5mil
Genie Costume - 3mil
Midnight Costume - 2.5mil
Vortex Costume - 4.5mil
Winter Costume - 4mil

Other
Homeless Fairy Doll - 3mil (?)