I have been taking yoga classes for over a year now and would really like to invest in a good quality mat. What brand would you recommend?

On Alliebags they have some lovely designs for yoga mat carriers and it says they are handmade. I'm sure you can find your wife something there http://www.alliebags.com/ALLIEBAGS/Home.html or take a look at the Etsy site; http://www.etsy.com/listing/62348759/xl-yoga-mat-bag-handmade

The thickness of a yoga mat is really a comfort issue. Also when you roll it up, thicker yoga mats can be harder to carry. Some people prefer mats that are thicker as they provide better cushioning, so body weight can also play a part in the decision.

It really depends what kind of yoga mat you need, but generally mats cost between $20 and $40.

Agreed with debbie. Jade is one of the best supplier of yoga mats. But if you want more variety then visit online stores or malls near you.
For more variety visit following link:
http://evolvefitwear.com/womencategory/yoga-mats-yoga-accessories

Gaiam sells a great basic yoga mat for beginners. I highly suggest taking a look at it. I will send you a link with more information about these mats that should help.

http://www.gaiam.com/product/68+yoga+essentials+mat.do