advice needed

I am attempting to make my own extension cables for my PCI wiresess card. I have a removable antenna with the reverse polarity SMA connectors. My question is where can I get the mini coax to make the cable. I have priced the various aftermarket extension that are out there but am concerned with both cost and signal loss should I have to connect more than 1 cable together to reach the desired location. Also, what is the proper name/ industry name for this cable. May I say thank you in advance for any suggestions or help that you can provide.

The types of coax cable you can use will depend on the size of the "inlet" on the connector. If you look at the connectors here:-
eBay.co.uk Shop - The WiFi Antenna Shop: Connector Crimps and Cable:
You will see that the "inlet" and the "crimp tube" can be of different sizes.
The "RG" numbers beside the connector are the types of coax that will fit.

There is an attenuation calculator here:-
Attenuation & Power Handling Calculator
You should be able to get a good idea of the losses with different coaxes from this.

You should be able to purchase coax from most electronic hobby or amateur radio stores, or you can always try ebay.