The price you may get depends on how badly the set is wanted. However I have been on the Bachmann website under,"ask the Bachmann", and many older H.O. sets don't bring much value, other than play value if they still work. Reasons given; not up to new coupler designs, also not up to new DCC control, so bottom line on there was not much value to most model RR people.
Just wish I could give you a more positive answer!
HI, Their is a web site that has information on Mantua/Tyco trains. They have parts. They might be able to help you on the value of your train set.
Their web address is www.yardbirdtrains.com