Unless you've got a Hub 4, you'll have to rent a VM booster at £3 a month. Over a year that's the same price as buying one outright that you could have delivered tomorrow by any competent online retailer.
But if you're spending £35-40 on a solitary booster that may not even perform well if the mains circuits in your house aren't favourable, then at least give momentary consideration to pushing the boat out to seventy quid for something like this that would be even better.
Other makes and models available if you don't like the suggestions I linked to.
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