For a start if your in a built up area I'd secure the router for your and them only, You'd need to find the MAC addresses of their systems and then restict acces to those and yours only, this way they wont notice a diffrence and you'll have exclusive access to the router (besides them).
Dont use WEP or WPA because you'll get busted right away
After that I'd leech their bandwith and save your cash. (as long as its a reliable connection)
EDIT: Sorry, didn't notice how old it was.
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