5000 BTU Air conditioner

i have a 5000 BTU AC unit, and it says annually it will cost like $40, but i highly doubt thats the truth especially since itll be running 24/7 at max power cause my garage stays really hot, so im kinda thinking about getting a bigger one. What im wondering is how much it would approximately cost for me to continuously run my AC all day every day for a month, cause i want to know if maybe it would be more worth it to get another one and have 2 but im not sure how much theyll end up costing after a month of usage.

For one about $45 a month for 12¢ a kWatt with pulling 515 watts for 24 hours on a 30 day period. Keep in mind if the entire ac unit is inside ur garage it will also produce heat.

5000 btu won't cool much in an open garage,hopefully u have an area of it sealed off or that lil ac isnt gonna do much

You should be able to find on any UL listed electronic device the volts and amp ratings. 5000BTU A/C ranges from 4.5-6A on a 120VAC (typically). 4.5A x 120VAC = 540watts or 0.54kW x hours of use.
540watts x 24hrs = 12,960watts used or just shy of 13kW/hrs. Take you kW rate and multiply ... 13kW/hrs x $0.12 = $1.56/day. Obviously if you are in CA/HI/etc and your rates are >$0.30/kW then it changes the price. @ $.30 it's $3.89/day

EDIT: things to note, HID's put off a shit load of BTU's, like 3k-6K BTU's, so add cooling as needed. Also, running a 5000btu A/C at max won't be quite as efficient as a 7500btu A/C running at 70%.

Okay so Im gonna try to do a couple things to maintain right now since its not too hot, but I'll prob end up getting a new ac in summer. First I'm gonna take the ac, which is back against a vent already, and build a small bof around the ac to make sure to funnel as much of the hot air out as possible, and The ac is just wide enough to be pointed in the vent of the grow room, so I was gonna cut out the tent enough to seal the entire ac in, and yes I currently have my exhaust just running throughout the top, so I'll get some more ducting and seal it going out another vent, and I'm running 24 hours right now so I'll switch to 18/6 and have the dark period be between like 11 and 5 to let the light cool down in the hottest time of the day. Also I know it sounds like a stupid idea but on the really hot days if I left the door to the garage open with the ac on for a long time could that cool it down at all?