Let me suggest a couple of budget options.

Trader Joe's Pound Plus chocolate bars are 17.6 oz and cost $4.99. They have milk chocolate and dark chocolate, but no white chocolate that I've seen.

You might also want to look into melting wafers. You can find them in the baking aisle of the supermarket. They are designed to be melted and reformed. They are usually used for fruit, like chocolate covered strawberries. However, they would work for bark as well. Ghirardelli makes them in dark, milk and white and they sell for about $5 for a 10 oz bag.