I don't know how to word that the query.
But as a work around, this (php) will do the job.
$db_database="database";//put the correct info in here
$db_password ="password";//and here
$db_user ="user";//and here
$link_id = mysql_connect("$db_host","$db_user","$db_password");
if (mysql_select_db("$db_database", $link_id));
$select = "SELECT column_name FROM table_name order by price asc ";//put the column name and table name in here
$results = mysql_query("$select", $link_id);
$query_data = mysql_fetch_row($results);
$number = $query_data;
echo "minimum number = $number";
What it does is get all the numbers, sorts them, lowest at the top, then returns the top number from the list.
Hope this helps