The budget for this opportunity is difficult to estimate without knowing the prices of the buses. However, we can consider the average cost of a new school bus, which can range from $80,000 to $100,000 or more, depending on the features and size. For used buses, the cost can be significantly lower, around $10,000 to $50,000. Given that the District is seeking 4 Type C SPED buses and 6 Type A NON-CDL SPED buses, the total budget could be substantial. Assuming an average cost of $90,000 per new bus and $30,000 per used bus, the total budget for the new buses could be around $540,000 (6 new buses) to $720,000 (8 new buses), and the total budget for the used buses could be around $120,000 (4 used buses) to $200,000 (4 used buses with higher prices). Additionally, the District is seeking trade-in values for four of its current buses, which could add to the overall budget. However, without knowing the specific details of the trade-in values, it's difficult to estimate the exact amount. Overall, the budget for this opportunity could be in the range of $660,000 to $920,000 or more, depending on the prices of the buses and the trade-in values.