hi you can book charcter meals directly with disney. we have just done the charcter tea party at the plaza gardens for £9 per person - very good value and food was good so was charcter interaction.
we have also done cafe mickey which is fron a set menu but cant remember the price of that one. again, character interaction was great.
if you go on the disney website there is a section for eat and greets with the characters as you can do breakfasts too.