Males tend to be kinder, or so I hear, Females can get moody at the worst of times.
Though, I'll admit, that I believe as well that most of it is individual personas.
Food.. Is mixed, I don't pay attention to my food bills.. but I'd say atleast $200 a month on meats alone... I raise 3 species of roaches, and when the heat is down, breed my own rats.. I'm not even counting what they cost to feed them (Though the Lobsters seem to subsist on left overs alone, I do buy Roach food for them)
Then the tons of greens I get weekly.. is.. rediculous.
But that's a full collection 
For a single adult Tegu, I'd imagine most of it would be vegetable and fruit matter, you could raise roaches (NO Smell! WOOT) as a supplimentry protein/calcium source.. with the occasional dusting, I'm not sure what species you're getting, but I understand depending on the species, they'll eat more or less protein as adults, as they have little growth left to do, and their diet will become abotu 70% plant matter, maybe more.
That said, I have no experience with Tegus... Just similar monitors, multiple Omnivores, and a Monkey skink...
So, yes, all guesswork.
Best of luck 
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2.5 Leos
2.1 Beardie
1.0 Burm
1.1.24 Common Boa
0.1 Sav (Bosc) Monitor
0.1 Monkey Skink
Wish for: Candoia Sp, Frilled D