Check out these units:
http://www.barcodehq.com/rfterminals.html

We use these and have had good luck with them.

The good things:
1. Require no programming on the handheld unit, you can do all your coding in Foxpro via ActiveX controls.
2. Interact with your data in real time rather than 'syncing'
3. Come in either Wi-Fi (100 - 200 foot range) or base station models (1,000 foot range)
4. Screens are impervious to sunlight (unlike computers, pdas, etc.)
5. 24 hour battery life using rechargeable double a's or regular double a's
6. Industrial grade (certified for 5 foot drops to concrete)
7. You can program your own voice prompts.
8. Dedicated numeric keypad

The bad things:
1. Not the cheapest solution.
2. The base station (not applicable on the wi-fi unit) is a serial interface which means you will likely need a USB/serial adapter on most any modern computer.
3. The display is a little on the small side.
4. Lack of QWERTY input keyboard (though each key is a unique letter so better than a cell phone)


Brandon