I am also new owner of a tegu in cold canada. this site
http://www.agamainternational.com/pages/tegus.html
has good pictures to determine if you have a argentine or columbian tegu. One question I have is what temperature you are keeping your tegu at? I am keeping my habitat at 29c. this could be why it is so lazy! as for building a habitat yourself this is what I did. I found tabletops for sale in Ikea's "as is" section. They were 3ft by 8ft which allowed me to assemble four of them into a 8x3x3 (length, width, height) enclosure with wood frame doors on the front with plexiglass. They were the best choice for me because they were water proof and had attractive wood grain and were cheap! I installed resessed lighting into the top for basking lights and a 48" flourescent fixture for uv bulb. I put lighting on timer and installed heat lamps as well on a thermistat. the substrate is 6" of hemlock chips (do not use cedar). I am able to maintain 29c temperatures with 3 basking lamps (75w each) during the day. The heat lamps (2 100w) only come on at night. The woodchip substrate holds moisture well allowing habitat to remain humid. Tegu is shedding well due to the humidity. tegu eats fruit everyday and protein every other day.
