TWO of these outdoor access points, Linksys WAP54GPE, one side of house and one on side of shop.  They cost aroun $400 but are powered and ready for outdoor installation.  In the house, run and ethernet from your existing router/switch/hub to House Access Point on outside.  Hand the one at the shop with line of sight to the house.  Run ethernet from Shop Access Point to shop switch/hub/computer.  Of course you'll have to have 110AC for each unit.  I have helped configure a mode like that once, and there is a certain configuration for two access points to talk, versus a configuration for and access point to talk wirelessly to other wireless computers.

Some companies offer "Cantennas" which do some of the same thing less expensively, and with some ingenuity, grit, and determination, you could probably get a pair of those to talking for less than $200 each, and build yourself a pair for around $100 each.  

Good Luck

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WAP54GPE.JPG (11KB - 184 downloads)

Linksys_WAP54GPE_DataSheet.pdf (85KB - 175 downloads)