Does hydronic radiant cooling work?

Hydronic radiant cooling can be done, but we would strongly advise against doing it in a humid climate. So we're not the ones to check in on about pricing since we aren't advocates of it as a technique to cool a home. Introducing a cooled-surface into a house, like a concrete floor, invites moisture problems as it can cause warm humid air to condense and put you at risk of mold and mildew forming. Here is a our page all about radiant floors as a starting place -

Radiant floor heat - Air heated, electric of hydronic, which is best? 

Even in the appropriate climate it is a fairly complicated system and needs to be carefully designed, and it would need to be coupled with a very good ERV to keep the Relative Humidity low. Alternatively, we would propose you simply use the floor for radiant heat, and cool the air in your house instead as is typically done.

Keep in mind, that a slab-on-grade floor offers a lot of thermal mass inside the home, so if you invest in a very efficient wall assembly and airtight building envelope, you can often wait out a heat wave (at least on the main floor) without the need for artificial cooling, as the concrete absorbs the ambient heat from the home. That and even a small localized heat pump may be all you need.