Thanks for the input.
I ended up getting the netgear XAV101 kit ($150) which is rated at 200Mbs. I installed the setup and found that they were only connecting at 37 meg. After trying some outlet swapping they now connect at 70 meg which is plenty fast enough for internet access in a garage. They work well. The only issue was when the garage compressor kicked on there was a slight interruption in the link but it recovered in seconds. Swapping outlets (circuits) solved this issue.
This is not the best situation for these devices. There is 150ft of wire to the house, noisy compressor, grinders, etc. and they perform better than expected. Can't complain at all. Much better than digging a trench or messing with wireless devices/ antennas etc.
Thanks again.