Bidding / account money managment scripts for a reverse bidding site.

Reverse bidding is a system where the lowest unique bid wins. So say 5 people bid for a $20 item, and they bid : $1, $2, $1, $4, $7 , the $2 bid wins because it is the lowest unique bid. Look at this website for an example [login to view URL] We are looking for a setup as such : Users have accounts that they add money into (through paypal or whatever, this does not have to be handled by the script, although if you can do that, brilliant) We setup a range of auctions where people can place bids on items, every bid costs a certain amount and when they bid that money is deducted from their account. When enough people have bid on the auction, it allows no more people to bid. The payment of prizes and the working out of the winner can be done manually by us, the script does not need to handle that. We do need to be able to add money into people accounts though. The database/transactions NEEDS to be extremely secure, obviously if people can alter the database they can make it appear that they have more money in their account and we lose money. This is extremely important, if you cannot demonstrate the security of the system it is worthless. When i talk about people adding money to their accounts and the system removing it, of course the 'money' is just the value stored in the system database. We can use any setup you wish, we have not setup the hosting for the site yet. On top of this initial payment we are offering a 20% share of our profits up to $1000. A very good grasp of english is essential, and a UK provider is preffered, although anyone who is skilled and speaks english well will be in the running. Any questions, feel free to PM or post on the clarification board. Alex