Cheap PCB service with castellated holes

[0xdeadbeef]

I'm sorry if that has been asked before, but I couldn't find any thread discussing this.
So in a nutshell: are there any Chinese PCB services which support castellated holes without massive extra cost?
I.e.for Elecrow, Seedstudio, PCBWay etc. the prices explode from $5 to $20-$25 for 10 very small PCBs (e.g. 15mm x15mm) when adding just a very few castellated holes.
I'm aware of all the technical issues, but I don't care if they are a bit messy.

[whalphen]

I've used OSH Park for this.  They are cost effective for very small boards.  They don't do true castellations, but they will drill and plate holes on the edge before routing.  This sometimes leaves extra tabs of copper in the castellation, but these can be easily removed with a small blade.  Look at this description: https://docs.oshpark.com/tips+tricks/castellation/

For a 15mm x 15mm board, the cost would be about US$0.60 each with ENIG plating and international shipping included.

[0xdeadbeef]

Thanks, I'll have a look. I'm just slightly scared that ordering from the US will cost me some hours at the customs office. I guess customs gave up controlling the massive amount of small packages from China while they always find the time to check stuff from the US.

[0xdeadbeef]

Anyway, I just ordered at OSH Park. As whalphen said, the prices for small PCBs are indeed very attractive.
I ordered two different PCBs, each 12x with ENIG plating and castellated holes (0.8mm FR4, 2 oz copper) and paid a bit less than 12€ since the shipping was free.
That's pretty much the best offer I could have hoped for.
If they put a proper customs declaration on the envelope, I might even get around wasting half a day at the customs office.

[0xdeadbeef]

The OSH Park PCBs arrived today. They posted them on the 7th of December and they arrived today (19th) which is pretty much what I expected.  It just took a bit longer than I imagined between order (27th November) and production. Anyway, I'm happy I didn't have to go to the customs office as they did a semi-legit customs declaration (fake $10 while I actually paid $12.80).
There was no bill/invoice included (which would have resulted in fun at the customs office) and the PCBs were just (loosely) put into the air wrap bag
Anyway, the PCBs looks pretty decent. The solder mask is slightly off (no issue) and they seem to have shrunk the ground ring on the bottom, so there's a small gap between ground ring and border. Surprisingly they didn't shrink the ground ring on the top.

Posted pictures in the project thread:
https://www.eevblog.com/forum/projects/driving-a-cree-q5-led-with-one-nimh-cell-anything-much-better-than-an-ltc3490/msg1974011/#msg1974011