Bicycle Tutor

I have a schwinn varsity 10sp that I'm fixing up and need to replace the rear shifter inner-cable. It has the shimano positron II derailleur which has a solid 'piano wire' type cable. I've found replacement cables for the positron on the internet... some indicate the bike model others don't. I did find one identified specifically for schwinn 10sp road bike, but was asking $35 just for inner-cable. Others just identified for shimano positron ranged from $3 to $8. Is there a difference in cables for the positron derailleur? Can anyone advise where I might find a replacement for a reasonable price? Would I be better off if I replaced the derailleur or would I also have to replace other parts (ex. cassette, chain etc)?

I appreciate any help you can provide!

If you are not a collector, I would replace. Your freewheel should be fine. I would replace the chain, rear derailleur and shifter, with a Shimano HG50 chain, Shimano TX51 derailleur and SRAM TRX shifter - all are available from Amazon and other sources for a total of less than $40-.

If you are not a collector, I would replace. Your freewheel should be fine. I would replace the chain, rear derailleur and shifter, with a Shimano HG50 chain, Shimano TX51 derailleur and SRAM TRX shifter - all are available from Amazon and other sources for a total of less than $40-.