Baby, it's cold.....

Baby, it's cold inside! Over the last few years the furnace has quit working every few months. We had to call a furnace repairman last year to fix it and he told us it was obsolete. He isn't aware of any place that sells the part we need. He showed my husband how to reset it when it stopped working but warned us that we'd need a new furnace soon. Lately it has been quitting almost every day so there are times when it gets downright chilly in the house before we get the furnace going again. I dread the idea that we may have to replace this furnace someday soon. I haven't priced them but I assume they aren't cheap.