I currently live on a lake and have my own well water. I don't pay for city water. So, I don't have much need for a rain barrel collection system at this time. However, I have lived in many places where a rain barrel collection system would have been a great way to store water and save money. I don't know how much it would cost to use metered city water for my gardens, but it seems to me that any investment in a good rain barrel collection system would pay for itself in little time.
Speaking of rain barrels, I don't know how much you have to pay for a new rain barrel, but last time I looked around where I live, they wanted over $50 for a plastic barrel. There might be another option to consider...
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I bought a few of these large totes when they went on sale earlier this year at Menards for under $20 each. I am thinking that these totes might also make excellent water storage units. You might be able to stack them on top of each other, or certainly on a rack, and take up less space than round barrels. Plus, if you want to clean out the tote, you just take off the top and have easy access.
If you want to add a spigot or something like that, it would certainly be easier on the tote compared to the round rain barrel. You can easily reach into the tote to add any number of connections.

I guess you would have to call it a rain bin system instead of a classic rain barrel system. But I am thinking there might be some advantages to using totes for water storage over barrels.
If you don't want those large totes, and they are very large, you could buy the standard sized 27-gallon totes...
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They go on sale all the time at the big box stores. Even so, at current regular price, two 27-gallon totes would be a lot less expensive than one 55-gallon barrel where I live.
I have lots of these sized totes for storage. Good value for the money and I love how they stack when full, and they nest into each other when empty saving lots of room.