ecommerce plugin for customized digital goods

hi All,

I am a freelance writer and write blogs, essays, articles etc. I have made a new wordpress site through which i want to offer my services. I need help in setting up the e-payment or e-commerce system so that my clients can visit my website and place orders. i have go through numerous ecommerce plugins available but most of them are for digital goods which are readily available.

All i am looking for is a plugin which can help me set up a client portal. There will be a client registration form, once the client registers into my website he can see his own member area. There he can fill a form to place an order. He can also see the details of his uploaded order. In my backend i should be able to respond to the client through email which he must receive on his account (with my website). After an agreement of price the client should be able to make payment through his online account with paypal or credit card.

After the payment is received i get the work done and upload the digital good into his account so that he can download it after logging in.

I am very confused. please help me to find the right plugin where i can basically sell customized digital products instead of a standard product.

For example: A piece of article’s price might depend on its length, writing quality and topic. So i should get the decide the price depending upon the requirement. and ths plugin should be compatible with any theme.

can anybody help me?

[Moderator Note: No bumping, thank you.]