Where can I buy some outdoor -> indoor cellular range extender?

I barely get 2,3 bars on the 1st floor, are there some affordable outdoor antennas that I can install to increase the cellular/mobile phone coverage at the ground floor / inner rooms?

Where can I buy this in Rawalpindi, Islamabad and whats the price point like?

as far as i know they are pretty much useless until you spend some big bucks.

i saw an antenna in hall road lahore for Rs 2000 and i don't think it would any good performance as a matter of fact the shop owner was unable to brief me properly how to use it , whether the Rs 400 worth of pannel would stick to the back of mobile phone or it would suck on it in a window as it has 4 suction bits to stick to an air tight windows pannel i guess.