user: Question: What is the average prize for the Buttercross Limited Stakes?
Columns: ['Race', 'Dist (f)', 'Course', 'Prize (£K)', 'Runners', 'Placing', 'Margin', 'Jockey', 'Trainer']
Types: ['text', 'real', 'text', 'real', 'real', 'real', 'text', 'text', 'text']
Sample row: ['EBF Cooperative Bank Maiden Stakes', 7.0, 'Doncaster', 3.0, 18.0, 1.0, 'Short head', 'Royston Ffrench', 'Luca Cumani']
SQL:

assistant: SELECT AVG("Prize (£K)") FROM "Table" WHERE "Race" = 'Buttercross Limited Stakes';