```python
def stamp_table(dies: list) -> dict:
    table = {}
    for fragment, price in dies:
        if not isinstance(fragment, str) or not fragment:
            raise ValueError("a die fragment must be a non-empty string")
        if isinstance(price, bool) or not isinstance(price, int) or price <= 0:
            raise ValueError("a die price must be a positive integer")
        if fragment in table:
            raise ValueError("die listed twice: " + fragment)
        table[fragment] = price
    return table


def stamp_cover(label: str, dies: list) -> int:
    if not isinstance(label, str) or not label:
        raise ValueError("a label must be a non-empty string")

    # Build the stamp table from the given dies
    stamp_table = stamp_table(dies)

    # Initialize a memoization dictionary to store results of subproblems
    memo = {}

    def dp(index: int) -> int:
        if index == len(label):
            return 0

        if (index, label[index]) in memo:
            return memo[(index, label[index])]

        min_cost = float('inf')
        for fragment, price in stamp_table.items():
            if label.startswith(fragment, index):
                cost = dp(index + len(fragment)) + price
                min_cost = min(min_cost, cost)

        memo[(index, label[index])] = min_cost
        return min_cost

    # Start the DP process from the beginning of the label
    result = dp(0)
    if result == float('inf'):
        raise ValueError("no sequence can spell the label")

    return result
```