For a start, would be nice to define what You mean by "VPN" — a bunch of options, this pptp, and openvpn, Easy VPN with IPSEC.
Secondly, you should know how the Internet comes to the point "HOUSE(Cheapest online)" if there is white IP, etc.
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In the simplest case, as already suggested above, any router with dd-wrt/opеnwrt, with support for openvpn/pptp.
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When selecting a router, you should pay attention primarily on the size of memory, because not every firmware wrt with vpn can fit in 16Mb. See the model from 32Mb.
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The perfect option for You to find out for themselves what is at the nearest points of sales (of the model), then to go to a website, for example, dd-wrt (
http://www.dd-wrt.com/site/support/router-database), to drive the model, read about the possibilities of firmware, read reviews, and decide.
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I suggest you look to LinkSYS — the ratio quality/price perfect.
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If you search well, for a reasonable price, you can buy a used cisco 800 series, there and flash third-party firmware is not necessary, and "cisco" as as.