I only use CS once in a while . Maybe twice a year for 3 days at a time. I would use In design, Adibe Illustrator and Photoshop. I am not in business and just use them to do cards for my grown up children. Can I buy a week's CS use now and again. Or even a month at a time? How much would this cost?
No. Creative Suite applications are licensed applications for which you pay once and the license is perpetual. You might be able to buy a temporary month's subscription, though a more practical/economical approach in your case would probably be to visit the local card shop and take care of your card needs there. If the creativity of creating cards is what you enjoy then you might consider just finding software specific to that purpose such as one of the American Greetings card creation products which are likely to be much less expensive.