Wireless phone jacks. Any ideas?

[Jhill]

I work in a convention center and people always want phonelines in very odd places (mostly for modems and CC machines) that are 50-75 feet away from the nearest phone jack. It's very time consuming running phone cord everywhere all the time so I need about 5 wireless phone jacks but the cheapest I can find them for is about 50.00 each.

I know that regular cordless phones are only about 15.00-20.00 so I'm thinking they can be had cheaper than 50.00.

Does anyone know where to get really cheap wireless phone jacks or how to modify a cordless phone into one?

Thanks