The first Alto (mostly designed and built by Chuck Thacker at Xerox Parc) started working in April 1973. The original cost target was around $15K in the dollars of that time. We eventually made more than 1500 of them (actually close to 2000 by some estimates) during the 70s.
I recall that the budgeting was actually about $22K per machine, which would be roughly more than $100K in today's dollars.
There are a variety of points here. The biggest one is that -- being a rather practical field -- we tend to have ideas that are possible. A factor of 10-50 allows us to have ideas that our subconscious minds reject automatically, because we are used to working within "normal". We have to shift or get beyond "normal" to make big progress.
Best wishes
Alan Kay