Take deeply to heart the advice about reviews of service. Some are great, some - well, great is the last possible descriptor unless adding some other less positive term.
There is a great need for some sort of regularization of the Extremely Wild West of the 3D printing world.
As a 15 mm gamer, I am appalled at what some 3D printers are willing to charge to convert from 28 mm to 15 mm. I know it can be done and I know it can be done a LOT cheaper than some do it. Sure, not everything reduces well - but the cost issue remains. And this is after taking into consideration the design cost. Some people are happy to rip people for whatever they can - with no regard to the reality that means for repeat business, like zero repeats - fast track to being out of business.
Of course, there are also highly reputable merchants and fairly priced product out there. That is where my repeat business goes. It is just seventy very angry Kodiak grizzly bears you have to get through to find them. Which, for me, makes 3D printed product a very, very last resort. But great when you can find what you want from a reputable merchant with fair pricing - and there is no other option.