create registeration form with custom payment

hello
i’m new wordpress user and i like it :d
i’m going to make website for sales vpn
i have many services for example 1 month—2 month— and other.to do this i need forms which users can be register into the site and then select a specefic service after this the payment page must be show which Amount is set to the specefic text box and in another fields user must enter the ideal ussername and pass for his/her account and from combobox user must select payment gateway for example Liberty or Paypal and the push buy button to redirect to the selected payment service
how can i do this? is there any module to do this????
Please help me