Unfortunately most suppliers seem to be in UK or US, so shipping is a killer.
aisc, don't forget that we don't know where you are!
South East Asia - currently in Bangkok.
I'm sure I have seen wire like this in Pantip Plaza but also tryhttp://www.wt.co.thhttp://www.mynpe.com/I think RS also have a Thai branch.
I already checked the RS web site - they don't seem to have uninsulated wire.
Tayda Electronics167 Soi 28 Rama 6 RoadSamsennai, PayataiBangkok 10400THAILANDCustomer Service Contact # : +662-6195817 ( Monday - Friday )
How about Farnell/Element14 http://th.element14.com/pro-power/tcw24-500g/wire-230m-solid-copper/dp/1230991?ost=1230991
What about Tayda Electronics.I've ordered from them and are very cheap. I forget how much shipping was.http://www.taydaelectronics.com/about/They are located in Bangkok as well.
I had quick look at their web site and could only see insulated wire.
Might also be worth testing a bit of CAT-5 cable if the conductors are big enough for your needs.