As suggested in lot of other answers, you can either buy it directly from the Dassault systems or the vendors that deal in your respective countries. One thing to note is, the cost of the package depends on the modules you want with your package.
What is Price Of Catia V6 Software and Where I can Buy It?
Catia Software Price
Dassault Systèmes,
Catia V6 Software is Developed by Dassault Systèmes, the software is marketed and sold through a network of Business Partners in each country.
Dassault Systèmes invited Intrinsys to become a Business Partner because of the unique opportunity to combine a sales/support service (the typical re-seller model) with a thriving engineering business, using the products on a day-to-day basis. This approach gives us the skills and understanding to support our customers in the best way possible.
First line support is provided by our team of experienced engineers, all of whom have up-to-date, real-world engineering skills. This support is backed up by our colleagues at Dassault Systèmes, both in the UK and the Global Support Centre in France.
Dassault Systemes or any other other competing organizations avoid giving the prices publicly. The best way to get the quote is to contact a Value Added Reseller (VAR) where you need to send in an email sending a request for proposal which includes the details of configuration you desire (License Type and Number of Seats).
Catia V6 Student Version :
The education version is available at a highly discounted price considering that the licenses cannot be used to develop designs or other outputs for profit. The education files again will be watermarked which disallows it being used on commercial packages. If you are enrolled in a college that uses CATIA then you may check if they have allowed access through VPN or have spare student licenses (promo codes) that will get you the access for free. If you still need to purchase the student version then you need to check V5 Student Edition for conditions of eligibility and prices.
Get Catia V6 Student Version Here:
HOW TO BUY CATIA SOFTWARE
For commercial packages you can always use this link where you will find the three options at the bottom of the page to get in touch with the right people.
Follow this link to get Catia V6