Let me start by saying I have never lost a plant in my life except one that I forgot to water in mid-summer in Arkansas and it dried out. I have had 2 money trees for 5 years now and have root pruned and re-potted on a regular basis. I repotted into new concrete resin pots a month ago and both money trees rotted. These are new styles of pots at a local nursery that combine resin and terra cotta to look essentially like concrete. I can't imagine that 2 hardy plants, growing in swaps in the wild, dying around 4 weeks after re-pot is a coincidence. The money trees were soft through the trunk with slimy green/white mold growing just under the thin bark.

Is it possible the pots were somehow at fault? They were absolutely brand new and I find nothing obviously wrong with them. My only thought is that the resin didn't hold as well releasing dissolved solids into the water. Combined with the naturally mineraly SoCal water the roots were unable to uptake any water and just rotted.

Resin just sounds toxic...like making micarta at home...

Maybe your trees were sensitive to the chems leaching out?

You could call the nursery and ask it there were similar reports, or just return for a refund if you have serious doubts. If it's some made in China unbranded product then who knows?

One thing I do for "questionable" garden products is test it with plants I typically grow. One attractively priced product is a composted steer manure blend that I can get for $1.50 per cubic foot. There's the standard advice that it should be avoided due to high salt content, but my trials show good results. I think there's a lot of gardening "knowledge" that is just people repeating things they heard from other people and it can be well short of the truth.

I will be going to the nursery to try to get a refund. The pots have a high quality debossing that says made in Italy. They seem to be very high end which is why I am so confused. When I first got the money tree it was in a pot with no drainage and it did just fine sitting in water.

My first thought was isn't resin a plastic and don't we grow plants in plastic pots?  So, I looked up up resin here: http://www.wisegeek.org/what-is-resin.htm
The first sentence says, "Resin is a natural or synthetic compound that begins in a highly viscous state and hardens with treatment. Typically, it is soluble in alcohol, but not in water."  The "soluble in alcohol, but not in water" kind of says the resin wasn't the problem. 
I'm just trying to picture this.  Was the resin used as a coating on the outside to give the pot shine?  I know you can buy the resin kits to coat surfaces with faux paint treatments to make them look like marble.  And terra cotta has been used forever for plants.  Honestly I'd look at the potting soil.  Any extra amendments?
It's gotta hurt to lose five-year-old plant twins.

There are some resins that are water soluble...but on a whole one would suppose, properly done, one made for plants should not leech...what is the brand?

I have been digging online and I think the brand is Ceramicas Lopez Blanco.

Does your money tree produce $10's or $20's??