```ts
export function fitBudget(prices: number[], budget: number): number {
  if (budget < 0) {
    throw new Error('Amount cannot be negative');
  }

  prices.sort((a, b) => a - b);
  let itemsBought = 0;
  let remainingBudget = budget;

  for (const price of prices) {
    if (price > remainingBudget) break;
    itemsBought++;
    remainingBudget -= price;
  }

  return itemsBought;
}
```