change orders

HELLO! What does data does everyone use when they are writing change orders. RSMeans and NECA? And how do you keep yourself up to date on it whenever the prices change? ex. making your own spreadsheet and every year changing the values or something different

Question, in pricing change orders, what factors do you usually include in your price? We are pricing a COD which changes 98 lines of a 272 line cable schedule and also adds 29 line items. The basement area is literally stuffed with duct work, our conduits were run on the ceiling 19 feet off...