If you want to build it yourself, you can get a vinyl liner steel IG pool for about $7500--in various shapes of the size you like. You'll have to get permits, get it dug, install it, etc, but you can save SERIOUS $$ by investing sweat equity instead.

Alternatively, if you have a flat (and I mean FLAT yard) you can put up a temporary pool like an 18'x42" Intex donut or donut oval and wait for them to hassle you. You then claim it's temporary and can take it down--or see how much the fine is and if it's worth it. 18' rounds sell on sale for about $300 to $500. lowestdeal.com has them instock for UNDER $300. 15' rounds are less then $200...If they make you take it down, it's not a huge investment and you learn whow hard pool maintenance is.

I can assure you that you get just as wet and just as cool!

If' you've got a fence it may be a while before anyone notices. Most HOAs try not to get too nasty about some stuff. Just threaten to sue them and they may back off. Find out if they've hassled people about kiddy pools and if not, you've got them. A kiddy pool is temporary--so's an Intex inflatable--you HAVE to take it down for the winter.