Pricing for custom plaster molds is tricky. I'm trying to get paid fairly and give you an excellent product at an acceptable price. Every mold is different and some shapes are faster to mold than others.
Having said all that I have been working on a pricing formula. It goes about like this:
$125 / mold part. That price is subject to go up or down depending on size. If it's small enough that I can just pour the plaster then I charge $100 per part. If it's larger and can only be frosted then $150 per part might be appropriate. That includes cost of plaster.
And then there is the bulk discount. If someone is hiring me to make a bunch of molds I am willing to cut them a break. Hey, finally, some job security! In that case I've recently been doing what should be more expensive molds for $100 per part.
Like I said, pricing molds is tricky. I try to make $25/hr when I'm making the mold. That doesn't include time spent talking with customers, gathering materials, etc. I come up with a quote with that wage in mind and honor it. Often, unforeseen challenges make it take longer than expected and in those instances I still honor the quote.
I can also be your personal 3-D printer. Send me a sketch and I can sculpt it and then make a mold of it. This is also tricky to price but in my mind goes something like, "Well, I think I could do that in 3 days, so 3 x 200/day = $600."
I double-box molds like you would ship fine art and haven't had any problems with mold arriving in the same condition they left the shop. Obviously, the size of the mold will determine the cost of shipping. Expect to pay about $80 to ship an average size mold (that could cast a tea kettle sized object) half way across the country. I tape the mold together so the parts don't vibrate. I try to have 2 inches of bubble wrap around the mold, with an additional 2 inches of bubble wrap to the walls of the inner box. The inner box is at least 2 inches smaller in every dimension than the outer box. Between the two I use biodegradable packing peanuts. I am at high elevation and supposedly the air in bubble wrap shrinks a little at lower altitudes. I still use it around the mold because it stays put, but I use peanuts when appropriate.