tack:
After seeing this I thought I'd email Sitopway for a quote.Just received it and they quoted me 50USD for 10pcs 100mm x 100mm dual layer, red soldermask, top/bottom silkscreen on 16mm FR4.
That's 20USD more than Elecrow, so looks like I'll be sticking with them.
The OP said 5.2GBP for 130mm x 140mm, so I wonder if that was just per single PCB, ie 10 pcs was 52GBP? That would make more sense at about 80-90USD for 10 pcs 130mm x 140mm, based on what they have quoted me.
the board was double sided, 5.2 each including postage 7 day turnaround, for a 130mm by 140mm board, 81usd total