Party supplies at the Party Monster The Party Monster is the UK's largest supplier of adults and childrens party supplies online, all with 24 hr UK next day delivery. We are an industry award winning seller of cheap party supplies, party decorations and party accessories. We have over 7000 party products available at amazing prices that are suitable for any special party occasion! Our fantastic range of party supplies includes everything from Superior Quality Latex Balloons and Foil Balloons to Hen Night Novelties and cheap Fancy Dress Costumes..