add extra payment method

I need a payment method added to my website. when members sign up they will have the option to be a buyer or a seller. Lowest Bidder gets the job. project must finish in 1 week. the website is [login to view URL] Buyer is 100% free bidding and freee registration Seller have different levels of memberships. which will be billed yearly. example of memberships this is what i need 1# when someone signs up to the auction website. they have the option to sign up as a buyer or seller. 2# the buyer is free comes with unlimted bidding. the seller has fees 3# seller fees will be: a) pay as u go which they will have to pay for all the extra features and final vaule fees. they will get a free store. b) bronze member a fee of $24.99 for the year will be charge and they will have a store with 1000 listings. also they will have decrease in final value fee and other features will be added c)silver member a fee of $44.99 for the year will be charge and they will have a store with 4000 listings. also they will have decrease in final value fee and other features will be added d) gold a fee of $74.99 for the year will be charge and they will have a store with 8000 listings. also they will have decrease in final value fee and other features will be added E) platnium a fee of $99.99 for the year will be charge and they will have a store with 10 000 listings. all features on the site will be free to the sellers. these memberships will all have features to them which will be free of charge.