Alternative to linear slides

Hello. I'm builing a router that should have in the Y axis about
2500mm (almost 100"). The price of linear slides, were I live
(Portugal) are about 2000 USD, with small slides (20mm) from NSK.
Ebay is not a solution, since the transport is also very expensive.

I'm asking to the list alternatives to linear slides to the Y axis,
if not to heavy (under 30 Kg). If I can build it myself even better.

Anyone ?

Thanks
Filipe Tomaz
http://mastor.no.sapo.pt