It's better to get the extra lean ground turkey. If you just ground up a whole turkey yourself you'd end up with too much fat for a healthy diet. A couple things to note, tegus grow super fast so are that much more prone to MBD. Proper diet and lighting is very important with these guys. You really don't have to worry about them getting obese when they're growing. I'll feed a young tegu until they look like they're about to burst and the next day they'll appear half starved. You should offer food daily(as much as they'll eat in 1-2 sittings) until they get to the subadult/adult range then you can cut back to 2-3 meals a week. The food bill isn't all that bad since they tend to hibernate 5-8 months a year. They don't always hibernate though and if your baby doesn't be prepared for the possibility of feeding all winter and providing housing for a 3-4 foot lizard within its first year! I wouldn't just feed turkey though, here's a list of acceptable foods for your GU - variety is the spice of life!
http://www.tegutalk.com/showthread.p...#axzz1gSN0F1qE