You might get a good deal by negotiating every last penny, but if you erode your contractor's good will, if something comes up in the future, he won't be too excited to help you and, in fact, he might be looking for ways to do it to you later. Get a good deal, but also be fair. Research can help you better understand the pricing models and limitations of your suppliers. Your suppliers have specific costs to cover, so starting a price negotiation and asking them for lower prices than what they can manage won't get you very far and may seem like a bad faith offer on your part.
That could affect the vendor's willingness to work with you to get any discounts. Or, you can dispense with complex negotiations and select pre-contracted offers from a portfolio of previously selected high-quality suppliers, such as Carrier, Grainger and Koch Filters, among others, where you can get discounts of 7 to 25%. Discuss the quote with the HVAC contractor and ask if there is room for negotiation. Be respectful and polite, but don't hesitate to ask for a better price.
Some companies may be willing to negotiate to win your business, especially if they're competing with other companies for the position. Be sure to communicate your needs and budget clearly and see if there are areas where they can save you some money. However, keep in mind that not all HVAC companies are willing to negotiate their prices, and you decide if their quote is reasonable and fits your budget. If the HVAC contractor isn't willing to provide you with an all-inclusive quote, it could be a red flag that it's not a reliable company.
While it can be difficult to try to get the lowest prices from your suppliers alone, some companies and products are specifically designed with independent HVAC contractors and small businesses in mind.