as far as I know, the current Taiwan models are worth between $100 - $120. therefore, you can roughly gauge the price of your DD-3. start unscrewing and start checking :lol: .
do note that condition, box & manual plays a part in the price. sometimes, you may get offers that are more than you expect since the demand for Japan DD-3s is relatively high.
do inform us what version it is, I'd be keeping an eye out for it .