I don't know about the OP, but in my opinion, it'd be anything less than or equal to an equivalent replacement part (if it were available--in the OP's circumstance it's not). For example, some manufacturers of vacuum cleaners easily charge in upwards of $20 for a small plastic piece that you wouldn't expect to pay more than $8 for. So, if on-demand 3D printing services could compete with that niche, it's something I could see being of use for aftermarket repair or replacement. Poorly designed plastic switches no bigger than your thumb shouldn't be more expensive than hose attachments.

The only thing to worry about is the manufacturers' response: I don't know how much money they make from replacement parts, but if it's anything other than a minor revenue stream, I'd imagine they might issue legal threats or takedown notices. I wonder if, in another 20 years, we'll see OEMs sending threats to 3D printing companies warning them not to sell replacement components even if customers sent them the schematic?

I just don't see this happening. Most mass market parts are made using methods that are very inexpensive and fast in large quantities: stamping, injection molding, and the like.

3D printing takes up a good amount of time on an expensive machine, plus operator time, electricity, shop space, etc.

Think about what your time is worth to an employer. The cost of a replacement part is probably relatively low compared to the cost of your time to fix the machine. Not to mention the opportunity cost of not having the appliance working.

You're talking about a situation where you'd like to get a price down to $8. It's very tough to make money selling physical products at $8 a pop, let alone things that must be custom made.

> Think about what your time is worth to an employer. The cost of a replacement part is probably relatively low compared to the cost of your time to fix the machine. Not to mention the opportunity cost of not having the appliance working.

My example was for an item in private use, not commercial. I don't know of anyone who actively bills for their own personal chores at home (such as, say, vacuuming or mowing their yard).

> You're talking about a situation where you'd like to get a price down to $8. It's very tough to make money selling physical products at $8 a pop, let alone things that must be custom made.

Maybe so, but you have to admit charging > $20 for a part that probably costs less than 50¢ leaves at least some room for competition, no?