Can you do it yourself a large rainwater harvesting system for not a lot of money? Yes you can! Start with used IBC Totes. I will summarize in this article and then go into detail in the future parts.
Begin creating a big rainwater harvesting system by finding a used 275 gallon IBC Tote supplier. Get as many tanks as you think you need. You will be linking them together for a combined capacity. I have 9 for a combined 2500 gallon. Cost was about $80 each so it was less than $1000 which is much less than a dedicated tank of the same size.