They can be hit and miss, especially if you buy low price range versions, but when set up properly these can be a life saver. This is just one of the cheaper ones I found with a quick search. Ive seen the benefits of a little more industrial version and was amazed; especially in the environment I was in. I understand you were looking for affordable, but if you consider a one time investment on an encompassing RF range at least you wont have to ever make the payments to your cell provider if you were to change a plan or change providers. Hope this helps..