Customer Registration/Login using MSSQL and online payment for Joomla

I require a Joomla module for version 1.5 that allows customers to sign up and pay for the service my business will provide. I am setting up the rest of the site myself but am seeking help with the integration with MSSQL and PayPal. I visualise the initial registration screen asking the customer to submit their name, email, mobile number and password which must be stored in a remote MSSQL server which I already have. However, before saving this information the user must pay a fixed amount (say 5.99 GBP) by credit card or PayPal through my PayPal merchant account. Only then should the data be stored. For a returning customer the Joomla module should also permit the customer to login using the email address and password previously provided (and stored in my sql server) with the ability to update a field which will trigger a password reminder email which I will arrange. Once an exiting customer is successfully logged in, the module should have the ability for them to change their details or to pay again if required (crosschecked with the SQL database) Hopefully I have explained my requirements enough for you to provide a fixed cost for development. I have my own Joomla 1.5 server running on Windows for testing. I am hoping for completion before the end of February. Regards