Going back a little farther in time, I just pulled out some 1887 mail order ads from Maher & Grosh. Prices include:
3.75" two blade jack, cocobolo $0.50
3.5" three blade whittler, ebony $1.00
4" four blade congress, bone $1.50 ivory $2.00 pearl $2.50
4.25" two blade cigar jack, ebony $1.00
5.37" two blade cokebottle, cocobolo $1.50
Most records that I have seen from that time show a typical days wages for a laboror (ranching, mining, etc) at about $1/day. So figure what you make in a day, (pre-tax, including benefits) and you have a rough idea what it would cost you today. If a construction worker makes $10/hour (and that is pretty low for around here) then that 1887 $1 knife would be about $100 or more today. So those $40-50 Case or Queen slipjoints look like a real bargain.
That being said, many of the near mint examples of slipjoints that I have seen from 100 years ago are generally better made than what we have today. Most had very good grinds, great fit and finish. Heat treating may have been a little more inconsistent, probably due to technology limitations, but the general construction seen on knives from the better manufacturers of the day was very good.