Once again it would seem that many here really don't understand how things get priced
IMHO very unfair assumption.
I agree supply and demand and current economic conditions can effect market price.
Condition affects price.The better the condition of original item . The more value.
Age may or may not and could affect the price either up or down or not at all.
I also know the price at a yard sale , a flea market, e bay and sotherbies auction house in NYC will likely be greatly different for the same item.
Time spent on a model or project certainly does affect value.
The skill level and efficiency of the builder also factors in here.
The mean wage of a machinist in the USA is about $20 per hour. This varies from state to state and with industry.
Does this mean if I buy a pm research kit for $ 72 and machine it in 10 hours I can sell the machined kit for $272 no because anyone can buy a premachined kit from PMR for $140.
Something like a lafrance or a locomotive is certainly worth a whole lot more than a simple single cylinder oscillator because of the complexity and the time involved not only in machining but assembly.
Hobby time or no IMHO it is an insult to value a machinist time at a few dollars an hour.
Gary of Cabin fever fame packed up from the Kinzer flea market early Saturday morning because he was tired of people trying to low ball his prices and give insultingly low offers.
Offers are part of buying and selling and a wise seller of used goods of prices high to leave room for negotiation. An experienced dealer will have a good idea of value going in and not price too high.
An I do agree with phil this is a hobby were are not here to make money . But I would like to think that my tools and models will not be treated or valued and junk , toys or run of the mill consumer products.
As far as the value of the lafrance IMHO the asking price is probably on the high end of value. IIRC a Louis Chenot american LeFrance went at auction for about what the seller is asking. And the offer made is on the low end. Ultimately the market value is what the two agree upon.