You can find decent flat bar index shifters all day long for around 20-50 dollars on ebay for various 6-8 speed shimano/sram components.

i'm looking to possibly buy a late '80s road bike frame that is missing its drive train and I am contemplating putting drop bars on it. I would be using an 8 or 7 speed cassette and either a double or triple with 52t big ring.

One of the reasons why i don't want to put drops is I'm not sure about finding inexpensive road shifters for drop bars. I don't want to spend 100-200 dollars for a set of brifters when I could just put flat bars on it and buy a nice Deore flatbar 8 speed shifter for around 30-40 dollars.

I do not want stem or downtube shifters, they are too uncomfortable for me.

So what did 8 speed road bikes use for index shifting back when they were popular and are they now fairly inexpensive as used parts?