Jlcpcb is getting very popular now, they are very cheap and the PCB quality is good (as agreed by many reviewers). You can check their manufacturing capability on their website.
For my order which was about 85mm X85mm four-layer board, and anything under 100mm X100mm, you get an offer of 5 PCBs for 28$.

The process itself is straight forward, you generate the gerbers as they recommend, upload the file, you will be asked to select different aspects of finishing and so, plenty of explanation about that online.

I choose to use DHL for quick delivery, the board took about 5 days to leave china after it arrived in Egypt, the process was quite weird, DHL asked about my national ID and after some 4 days it was released, the shipment to Egypt costs 28$. For Clearance and customs, I paid about 900 LE which is quite high for the order.