Rainsoft AMB 744 CT 60HZ replacement

I live in Houston, TX. The rainsoft system I inherited when I purchased my house died a few years ago and I am wondering should I replace just the valve with a Fleck 5600 or another valve or should I replace everything. I have a $500 budget. I have attached a few pics of the current system.

Thanks for your suggestions.

The tank looks to be about a .5 cubic foot at best.. I have seen some of the older ones that there was really no way of getting the media out of the tank.
Most likely you would be ahead if you changed out the system with either a used one that might be in your area or on Craigs list or even E bay as some one selling a used one on the cheep or even a new unit that has the 5600sxt and called the 32k unit.
It most likely will take awhile to find one in your price range but if you wait and search you should be able to get what you are looking for.

The real question to ask is, "Do I need water treatment?" You probably do, since Houston was #6 on a list of the 10 worst cities in terms of water quality a couple of years ago (http://www.dailyfinance.com/2011/01/31/ten-american-cities-with-worst-drinking-water/), but you can't just go buying a "system" without knowing what problem you're trying to solve. Houston, like all municipal water systems, publishes an annual water quality document that includes lots of contaminants, but doesn't include hardness, so you should test that yourself, then combine that with Houston's current report, and you'll know what you need to treat for. Judging from the 2011 report (Houston does an excellent job of hiding the 2012 report, if it's available), I would want to get rid of the chlorine (4ppm), just for aesthetic reasons.

Also, check to make sure Houston even allows you to do treat water yourself. Softening, in particular, is banned in some municipalities.

Can you produce a list of those places other than the couple in Calif?

Nope. That's why I said "some". But I think we'll be seeing more of them as time goes by.