Welcome to the forum!
Keep in mind that the heater won't actually run 24x7. My 4x4 tent is in my basement. The basement started out at 67° when I started my first grow, but has dropped to 60° the last few weeks. The heater in my tent only runs for a short time, maybe 2 min every 10 min. to keep the tent at 77° So, it's not really pulling 1,500 watts x 24 hours. Actually it's not even running on the 1,500 watt setting either, it's on the 750 watt setting. So the real power consumption is 750(watts) x 24(hours in a day) x .2 (only running 20% of the time) = 3600 watt hours per day = 3.6kwh per day. Multiply that by $.11 (my cost per kwh) = $.40/day = $12/month to heat a 4x4 tent to 77° in my basement.
I run a "2000 watt equivalent" LED light that actually pulls 300 watts for 18 hours per day. That's another 7.2 kwh per day or $23.76 per month.
The next biggest draw I have would be my exhaust fan that pulls something like 1/3 of an amp. But like the heater it only runs when the Inkbird controller turns it on. Then there's the humidifier that runs on and off the first several weeks of the grow. I don't know how many watts it pulls, but it can't be much. Let's just call it the same as the exhaust fan and say they both run 50% of the time. I also have two circulation fans in the tent. I think they pull something like 17 watts each. So, round that all together and you get something like 72 continuous watts = 1.7kwh/da = $5.61 per month.
All together my grow cost me something in the neighborhood of $42 per month in electricity. Also, I spending about $30/month on distilled water because my water sucks.
Setup cost on the other hand... a quick tally from my Amazon order history says I've spent around $812 for my grow tent, humidifier, light, controllers, pots, coco, fans, nutes, etc. That's not counting the heater, power strip, extension cords, etc. that I already had or bought locally.
Add it all up and that puts the cost of my first grow at just about $1,100 or $110/oz. (if I get 10 oz out of this grow, fingers crossed but not counting on it) But if I don't buy anymore equipment my future grows (assuming 10 oz per grow) should be around $35/oz.
I figured a lot of this before my grow to make sure my entire tent could run on one 15 amp breaker, but I've never added up my other costs. So this was a good chance for me to do that as well. Hope that helps you make your decision. Good luck!