There are indeed commercial outfits that do 3d printing. I have no idea what they'd cost since I have my own printer, but I'm guessing that pricing is a combination of a per-job fee, plus a cost for the time spent printing, plus the cost of filament. I've heard a rumor that some public libraries have free 3d printers for their members. A box I recently designed can hold a couple of power converters, a small ARM SBC, and a dozen 18650 cells ... it used 50 grams of filament, or about $1 worth of plastic. Printing a more appropriately sized box would probably be about $0.25 worth. You could use something like tinkercad (online) or openscad (free, multiplatform) to design your own box, download some from thingiverse, or just buy a ready-made electronic project box (< $20).
I'm looking at an $11 ublox6 (
https://amazon.com/Navigation-Positioning-Microcontroller-Compatible-Sensitivity/dp/B084MK8BS2/) on Amazon right now that has both usb and uart+1pps outputs. While the raspberry pi might be in short supply right now, you could look at similar SBCs: NanoPi, Le Potato, orange pi, radxa, ... My radxa zero is connected to the aforementioned ublox. If you don't mind plugging a few dupont connections you could probably put together a few on the cheap.
Sorry, it's not a commercially supported, low cost ntp appliance... Hopefully you get some use from our suggestions.