Add shopping cart to already made inventory system

I am looking to subcontract out a part of a project I am working on. Basically what I need done is to have it so that people who goto [login to view URL] and then goto the DVD section, are able to add these dvd's to their cart and buy them... a full-blown cart is not needed with inventory control and all that... The client that uses this site is able to use a CMS i built for them to add their DVDs on the site already. below are the main tasks that would needed to be done, obviously some of them require some backed database work...all info will be given to chosen bidder. CMS modifications: -Turn DVDs category into 3 types: DVDs - Music , DVDs -Documentary, DVDs - Adult -make it so that DVDs have a check box if they are for sale -make it so that DVDs can have a price if they ARE for sale Front End Modifications: -Make it so that the DVD section has a drop down box to filter the dvd content.... Music, Documentaries, Adult -add a 'add to cart' button on each DVD details page Cart Creation -DVDs only will be able to be added to the cart for now....needs to be able to expand easily to other albums in the future -the purchaser must provide their shipping info and billing info (credit card only) -orders will send an email receipt to purchaser -orders will send an email of order request to client (tapekingz) with shipping and billing info -Billing info and order info will have to goto the client's merchant account, they use: payment tech (which is a part of chase) PREFERRED: ANYONE WHO HAS USED PAYMENT TECH TO DO ONLINE ORDERS hope this is clear enough, any questions let me know...im looking for fair bids, as i have a limited budget for this, but open to fair suggestions