It may depend on where you live. The price for older singers has gone up in the last 3 years in my area. I paid about $35 or $40 for one about 4 years ago but I can't find one for under $100 now. (I gave my first one to my son and the only way he'll trade with me is if I trade one of my featherweights with him....humph! Obviously I've trained him to enjoy older sewing machines.)
I haven't bought another 99 yet because I feel that $100 is too much at this point in my life. In one way, it isn't too much because the machine should last my lifetime and I've bought things that would only last 10 years for that price so why not the singer...but I'm still trying to figure out why all of a sudden people love the older machines. (I've loved them since I was about 10 years old and have been picking them up, fixing and then giving them away to friends and family for the last 10 years.)
I live in the northwest. In other areas of the country, the 99 may be going for less than up here.
Kathy