The Simon Yorke is a bit out of your range, but you may like this baby:
Any AC turntable can be run on batteries.
Until recently* I made a kit which was specifically designed to run AC synchronous motors on SLA battery supply. It's very easy to do, use a car amp chip to step up the oscillator power then transformers (one per phase) to convert the voltage.
*I stopped selling the kits last week.
I would go the traditional route of serious off grid users. Buy a true sine wave power inverter and use 12 volt DC deep cycle (RV/Marine type) batteries. That will allow you to use your existing 120 volt AC equipment without deriving power from the grid. You would use a solar panel (cheap) or windmill (not so cheap) and a controller to charge the batteries. With the batteries charged you can run the inverter and to listen to your system. Keep in mind that several high end companies make power regeneration systems that are effectively taking ac power from the wall and regenerating it with a true sine wave inverter. You will get the same effect here - clean AC, but with the bonus of not using power from the grid. You must use a true sine wave inverter - not the cheap units at Wally mart or you could damage your equipment. If you want to use car audio amps, they can run from directly from the batteries and everything else could run from the inverter which would require a smaller inverter. If interested in this method, I can help with details and/or point you in the right direction. I've done it and still have the equipment.
We use an RV battery like Bradearles described with our Teres, and with its DC motor no conversion is required. As Selfdivider said, Teres belt drive models all run on battery, as do Galibiers and Redpoints. But they're all way beyond Shazam's budget.
The entry level Amazon was a good suggestion, check with Mehran at Sorasound (advertises here). Look into Scheu tables as well.
I own a Scheu Analog Premier MkII with the battery power option. It will be over your budget but the Scheu Cello should be fine. It was the table I considered prior to getting a deal on a used Premier. Tom Hills at Hudson Audio is the importer and can help you with arm/cartridge combinations for Scheu tables.
Just to be devil's advocate here - and maybe save you some time, money and grief -
No part of ANY turntable's signal path is on the grid. The current is generated purely by the movement of the magnets and coils versus one another. So all you would be doing is using a battery to spin your platter - the speed of which is already electronically regulated very accurately.
Now, I'm not going to get into a big Audiogon argument about the nature of momentum, speed regulation, and platter mass - many audiophiles have vivid imaginations, but IMO there is absolutely no way that powering properly designed belt drive TT (which will have a heavy platter and isolated motor) by battery can possibly have any discernible effect.
Opalchip, you make a good point - I guess hadn't really thought this all through properly. I live in an old house with old wiring that creates a lot of noise pollution - even through my power conditioner. My solution is to take all my equipment off the grid and I made a newbie assumption about the turntable.
Arguments over regulated power to the motor notwithstanding, so long as I have a solid piece of equipment, I shouldn't get any DC noise in my signal path - which is my main concern.