a 100w basking bulb on for24 hours a day will cost only about 4 dollars a week.
thats 24 hours.
blue tongues even bearded dragons will only need 8 to 12 hours of heat a day, summer, probbly less.
invst in a thermostat and get a ceramic emiter, you will get return on investment with in 12 months in terms of power saving.
a small reptile bulb will cost only 2 dollars a week to run if its on 10 hours a day.
the cost of running a reptile tank is cheap. in fact, reptiles are cheaper to keep than fish.
except maybe turtles - they need heated water, even then, its on ly 22 to 25 degrees of water turtles need.
i think you are overestimating the cost of reptile keeping, i reckon go for it, you will enjoy it