Develop a Gift voucher module for Drupal

We are using Drupal 7 commerce version. There is a module that i think we could build on [login to view URL] My client has some additional needs too - listed below The site is still being built and has run over time because I used a developer who had a day time job. I really need someone who can help us develop this module full time and provide part time support to the continued development of the website. Client's wish list 1. In order to access and print your Gift Voucher(s), you will be provided access to a webpage that contains a link to your gift voucher(s) - We have the design for this already 2. A pdf version of the Gift Voucher will be sent to the purchaser, or the recipient if a user account has been created for them. As above. 3. Once a customer has purchased a gift voucher, the recipient will be able to use it on the site based on the following rules:- a) If a gift voucher is of value less than the total cost of the booking, the voucher will be completely used. The recipient will be required to pay the outstanding amount using the usual payment process; b) If a gift voucher is of a value more than the total cost of the booking, the voucher will be partly used. The recipient may use the remaining amount of the voucher at a later date (subject to condition 3C as set out below); c) The gift voucher will be redeemable for a period not exceeding 18 (eighteen) months from its original purchase date; d) A recipient can apply as many gift vouchers as required to a purchase as long as the total value does not exceed the cost of the booking; e) A recipient can enter a gift voucher code(s) at the checkout page on the website. 4. If the value of the item(s) you purchase is greater than your gift voucher, you can pay the balance online. 5. Any credit on account, redeemed from the purchase of an original gift voucher will only be valid until the original expiry date of that gift voucher, not exceeding 18 (eighteen) months from its original purchase date. 6. All gift vouchers will be valid for a period not exceeding 18 (eighteen) months from the date of its purchase. After this date, the voucher and any credits due will have expired and be void. From the list provided do you think you could give me an estimate of the amount of time required and when you would be available to start. Thanks for your interest.