The Turnigy 9X or 9XR would be good choices. The 9XR is fairly new, and has some teething issues, but has very good software and is very extensible. The 9X requires some modifications, but is one of the most well-regarded radios and even with all the add-ons you'd need is still an incredible value for the price.
If you got the 9X you would want to get a "Smartieparts" board, a backlight, a transmitter battery, and the OrangeRX DSM2/DSMX module. You'll then want to flash the firmware on your radio to use better software like ER9X. I would recommend getting the 9X without the module if you intend to only use Spektrum receivers. The version with the module uses a good TX/RX system, but the module is hardwired in, and is a pain in the rear to remove.
If you get the 9XR, at this time you'll need to get the OrangeRX module, a battery, and an AVR programmer. Eventually the 9XR will have an inbuilt Spektrum module, but it currently comes with no module.
Either way, figure about $150-200 total with shipping.
The DX7s is a great radio, and what you are paying for is good service and something that you can use out of the box. The Turnigy radios are much, much cheaper, require a bit of fiddling, and can have less quality. It all depends on what your priorities are - if you don't want to fiddle with your TX, the DX7s is a good radio. If you're OK with doing some work and want to save a lot of money, the Turnigy radios are a great choice.
I have a DX6i and a 9X (and a 9XR on the way!) - both are great radios.
I do highly recommend using the OrangeRX receivers sold by HobbyKing - they are a fraction of the price of Spektrum receivers and work just as well. If you're going to fly long ranges get a satellite receiver and mount it 90 degrees to the primary antenna. But for just a parkflyer, all you need is a basic OrangeRX receiver and you're good.