Do you have existing gear or are you looking to get some?
You can setup a mesh network with products from
Open-Mesh Wireless Network | Affordable Wireless Solution | Open-Source / Ad Free or
Meraki Wireless Network | Affordable Internet Solution | Free WiFi. With these they'll both talk to each other and act as an "extender" of your wireless while both communicating with each other. If you have more then you can get a true mesh topology happening with them talking to each other.
I've got a couple setup and they are so simple it's not funny and mine work well. The only hard part is you'll have to buy them from the US and import them but the price is still reasonable at $39USD plus postage upwards.Sometimes there are some on Ebay but you have to keep an eye out for them.
If you want to get over 50metres line of sight I'd suggest removing the antenna that ships with it and get yourself an external antenna.
I got some background info at
Merakeye.com - Enthusiasts watching Meraki, Open Mesh & Wi-Fi developments (Australian?) and have one of each. I prefer the open-mesh as it's a bit more hackable and not locked down like the Meraki but if you are just starting out Meraki is very straight forward and simple to setup.