Auction site

I have a client who requires a simple but very effective customised Auction site with all the usual security and payments (paypal), my client hasn't given me much apart from the following information: Scenario A - School auctioning their second hand equipment School buys in 30 PCs for a classroom and sells their 30 old PCs via the the auction site. The auction lot sells for £1,000 incl VAT. Client takes care of the money transaction with the buyer and arranges for the pick-up and delivery to the buyer. VAT is deducted = £148.94. Delivery costs (eg £50) are deducted. Original AV retains 7.5% commission from the remaining balance = £48.91. The remaining balance of £603.21 is available to the school to spend with client on future purchases! Scenario A - Pupil auctioning their second hand equipment Pupil auctions off their second hand PS3 via the auction. The auction lot sells for £100 incl VAT. Client takes care of the money transaction with the buyer and arranges for the pick-up and delivery to the buyer. VAT is deducted = £14.89. Delivery costs (eg £10) are deducted. Client retains 15% commission from the remaining balance = £9.03. The remaining balance of £51.19 is paid to the seller. The £9.03 is divided between the pupil’s school and the client (10% to school, 5% to client). £6.02 share is available to the school to spend with client on future purchases! Hope that makes sense but if you have any questions let me know. the project has to be completedquickly as possible. Thanks.