Heng Long
http://www.rccommand.com/tanks.php makes both the StuG III and the PIV, but you'll have to scratch the side skirts. Depending on where you buy your Tamiya tank and add to it, here's a good example of them only costing $700.00.
http://www.aaftankmuseum.com/panzer4RC.htm
Very reputable companies too to deal with!
- Jeff