Startup Idea : Trade concept,consumers and manufacturers

A concept for an online trade platform. To bring manufacturers and consumers together in a new and exciting way. Example...A manufacturer would list wholesale 100 watches for $5000.,Value of each watch being $50. Retail value being $500. The consumer would make a deposit for the watch and enter into a group sale,as another consumer makes a deposit the number of sales on the 100 watches goes up. Once the sale for the 100 watches is met then the remainder of the deposit is collected and the sale goes through to the manufacturer as a single sale. It would be the risk of the manufacturer to honour the sale after 10 days no matter how many watches are sold. Cost of watch would include postage to Australia. Additional delivery cost within Australia would be calculated based on weight and postcode. The delivery service within Australia would be outsourced. PayPal would be the best solution for finance transactions. The group sale of 100 would add an element of excitement to the consumer as they would be able to monitor the number of sales taken,also they would be able to share the sale with liked minded friends etc. I would love to hear of any feedback you have for this concept.