I priced out the tanks as we want to get one too.

2500g is the tipping point where price goes up significantly. I believe 2 x 2500g tanks are cheaper than 1 5000g tank.

Can you not just put it under some trees?

I think a shed would be cheaper and easier than concrete, and you can make it a bit larger to store other goodies inside too : )

Please, if you do this post pics and info I would love to do a 2500g tank this summer.