welcome
check averages on fleabay and others, but be warned, fleabay "used stuff" prices are generally too high, mostly because you have fees to pay, and sadly packing shipping,, sold as is no return etc ...
and since you're new here with zero post(s) or no reputation, it may be difficult to sell here ...
racal 1991 1992 etc suffers from keypad switchs problems, and need to be tested, unless it was repaired (they almost all do that, some had better switchs in some production batches)
take pictures and show their state ...