If you or yours use the pool alot, it probably will be worth it to you.
If it's in chitty shape now, you'll probably need to get it refinished (diamond brite probably, marcite is passe.) If you do that , throw in one of those color brite lights that change colors. refinish is $2200 to $2600 in my part of the country. This should last 10 years or ++. The new bulb is like $220 wholesale(they are available direct) and $350 retail, and you'll love it.......probably the best money you will spend
If it's unscreened, you'll probably want an auto cleaner, $200+ to $400+.
After it's under control, you can probably take care of it yourself. A bucket or so of chlorine($4-5) a week, a cup or so of acid per week, some sodium bicarb once in awhile. The most expensive will be some stabilizer, about $20 twice per year. This will preserve whatever chlorine you have in there, actually saving you $$.
Water bill is negligible. Depends upon municipality, of course, but the last time I filled mine, a standard 15X30, about 10 to 12,000 gallons, it was between $40 & $50.
The big buck guzzler is the pump and the electricity involved with that. My meter spins like crazy when it's on. Some places will tell you to run it 8 hours per day...........I find that not necessary. I do 4 hours during the S Fla winters and and maybe 5 hours during the summer and that works just fine.(mine is screened in, tho) If yours is unscreened,under a tree, etc. you will have to adjust that time upwards to properly clean & filter.
The cartridge filter if yours has one is a bit pricey at $75 on up, mostly up. A good clean filter will reduce the load on your pump, cutting electricity and extending it's life also.
Pool stores will tell you to change this once per year..............then again, I find I can get 2-3 years from one. They just want to sell supplies, of course.
If you take care of it yourself, it is very imperitive to find a good & HONEST pool store to buy your chemicals from & to give your your readins from the water sample that you bring in.
I am lucky here, I have one...........9 times out of 10 they tell me my readings are good and send me on my way with nothing or just my regular order of chlorine & acid.
Some won't do that, they like to sell all sorts of extra stuff. Hey, keep in mind that your readings don't have to be perfect every time. A little "off" here or there won't matter a bit. Your hair won't turn yellow and no one is going to get sick from it or swallowed up by it and drown unexpectedly.
An optionto the chlorine hassles is a salt system which is about $1200 to install. I don't know too much about these systems, I have never had one.
All in all, if you enjoy it, it's worth it as you can keep costs to like $12-$20 per week without figuring in electricity or major refinishing costs.
A last thought: If you have an auto cleaner with a screened in pool, it's not necessary to run that cleaner 7 days. 3 will be good and you will also extend the life of your motor that way
GL if yoiu choose to go that way.