SELECT b_iblock_element.ID,
b_iblock_element.IBLOCK_SECTION_ID,
b_iblock_element.NAME,
(SELECT PRICE FROM b_catalog_price WHERE PRODUCT_ID = b_iblock_element.ID AND CATALOG_GROUP_ID = 1) as PRICE_REGION_1,
(SELECT PRICE FROM b_catalog_price WHERE PRODUCT_ID = b_iblock_element.ID AND CATALOG_GROUP_ID = 2) as PRICE_REGION_2
FROM b_iblock_element
WHERE b_iblock_element.IBLOCK_SECTION_ID = 28
GROUP BY b_iblock_element.NAME;