Help with sorting custom query

Here is a sample arguments array for the query I am performing:

Array
(
[post_type] => product
[orderby] => menu_order
[order] => DESC
[nopaging] => 1
[tax_query] => Array
(
[0] => Array
(
[taxonomy] => product-category
[field] => id
[terms] => Array
(
[0] => 8
)

)

)

[meta_query] => Array
(
[0] => Array
(
[key] => product_price_10
[value] =>
[compare] => !=
)

)

)

I am currently ordering by menu_order but I want to actually order by product_price_10

This query is looking for products in a specific category (custom taxonomy). My plugin also has price levels where a single product can have multiple prices, 10 is the ID of the price level currently being queried.

I have tried the following but it returns no results:

Array
(
[post_type] => product
[meta_value] => product_price_10
[orderby] => meta_value_num
[order] => ASC
[nopaging] => 1
[tax_query] => Array
(
[0] => Array
(
[taxonomy] => product-category
[field] => id
[terms] => Array
(
[0] => 8
)

)

)

[meta_query] => Array
(
[0] => Array
(
[key] => product_price_10
[value] =>
[compare] => !=
)

)

)