^ I assumed we were talking about non-terminated bulk cable. I would not go to the trouble of burying terminated cables to merely save putting in a wall jack.
However, 150ft solid core, terminated, direct burial CAT6 cable w/PE insulation isn't hard to find either, $55:
As far as unterminated, there's also gel filled cat5e 250ft $48/$50:
Amazon.com: LinkedPro 250' Weatherproof Waterproof UV Rated Direct Burial Gel Filled Network CAT5e Cable W/Solid Copper Conductors: Computers & Accessories
www.amazon.com
Gel Cat6 250ft $69:
Buy CablesOnline 250ft CAT6 23-AWG 100% Pure Copper Gel Filled Weatherproof Direct Burial Outdoor Bulk Cable, Black, U6-B250D: Cat 6 Cables - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
www.amazon.com
Why go to the trouble (expense) of using adapters? Direct burial cable is not hard to find and quite capable of a <150ft run, unless something less than GbE speed is acceptable and it already had a powerline run which was viable.
I don't know which powerline ethernet adapters have good performance at 150', but I'd guess you'll get less than 500Mb throughput. I could be wrong, tech gets better over time.