I don't think you should be too worried about the cost to fill it. (You only do that once) It is the maintenance!! That is what cost you, both in money and time. We have had our pool for just about 20 years. You have got to really be dedicated to pool time. It takes at least one hour a day to maintain an above ground pool. We had issues with our cover over the winter and my husband took the pool covers off Sunday. He has already started the filtering system for this season. So....already the filter will be running at least 5 hours a day. Not only that cost, but the shock treatments, the stuff you have to put in to keep the water clean, the net thing to take out leaves, all these things add up. You also have to check the water daily to make sure all the colors turn the right color on the "checker" paper. lol (don't know what it is called)
One of our neighbors got a pool about 3 years ago and he took it down and threw everything away because he could not keep it going. All that money right down the drain.
I'm not trying to discourage you ktreas, but it really IS a lot of work. (My husband has informed me that since I am retired now (dang it) I get to do at least half of it)!!