SQL запроса:

SELECT   wp67_posts.*
					 FROM wp67_posts  LEFT JOIN wp67_term_relationships ON (wp67_posts.ID = wp67_term_relationships.object_id) INNER JOIN wp67_postmeta ON ( wp67_posts.ID = wp67_postmeta.post_id )
					 WHERE 1=1  AND ( 
  wp67_term_relationships.term_taxonomy_id IN (291)
) AND ( 
  wp67_postmeta.meta_key = 'average_price_week'
) AND wp67_posts.post_type = 'boats' AND ((wp67_posts.post_status = 'publish'))
					 GROUP BY wp67_posts.ID
					 ORDER BY wp67_postmeta.meta_value+0 DESC
					 

Первые 20 постов и meta:

ID: 1202 — title: Sunsailor — meta: ['3080']
ID: 1196 — title: SANDOKAN — meta: ['1180']
ID: 1194 — title: Helix — meta: ['1260']
ID: 1192 — title: Salona — meta: ['2812.8']
ID: 1189 — title: Storm — meta: ['5520']
ID: 1173 — title: Kraken — meta: ['9840']
ID: 1169 — title: NEW DREAM — meta: ['5184.2']
ID: 1156 — title: No name — meta: ['2920']
ID: 1154 — title: NO NAME — meta: ['2750']
ID: 1150 — title: PROMOTIONAL — meta: ['7560.8']
ID: 1146 — title: SANJA — meta: ['5814.8']
ID: 1143 — title: Romina — meta: ['1500']
ID: 1140 — title: Odi — meta: ['1300']
ID: 1132 — title: Carol — meta: ['2400']
ID: 1126 — title: Nana — meta: ['1138']
ID: 1106 — title: Blue Dream II — meta: ['2600']