“Sorry, you can’t get that here. Nope, we don’t have that either. Never heard of it. You want what? When? How about this instead, it’s what all the contractors are using.”
You can see how this could go on and on. Just like having reliable subcontractors, it is important to have reliable suppliers who are willing to go the extra mile for you. In general, large supply yards have access to all kinds of items they don’t normally carry. They simply need to special order these materials for you. It will take more time to get these in; however, you should not be told it is impossible. Of course there are always exceptions and it is quite possible that what you are asking for really is nuts. In that case, you may want to consider other options.
Try to shop locally. This means avoiding the big box stores like Lowes and Home Depot. It’s not that I have anything particularly against those stores. In fact, I have used them myself in the past; however, the service you get at a local market will be better and is worth paying a little extra for. I would not recommend the tiny store on the corner for your major orders, but I would use them for the in-fill orders. By this I mean the things you forgot on your initial order or discover you need mid job. This might be a few extra 2x4s or some nails. Sure it’s not much, but if you can create a relationship with more than one yard, that is a good thing.
As with everything in construction, your relationship with your suppliers will be important. If they know you and like you, you will have a better chance of them working hard for you to find something out of the ordinary. That extra service could be a life saver in the end. I once had a job where I needed a super flexible base trim to curve around a tight curve in a straw bale wall as it met a series of full wall height windows. There was nothing in my local market, but my supplier found a material that would work. No one else had ever used it that he knew of. It worked perfectly and he was happy because I gave him the feedback he needed to better sell the material to his other contractors. Win, win.
Take the time to find the right suppliers. Don’t go with the cheapest unless you believe they can provide you with excellent service. You may find in the end that they actually aren’t that cheap. For example, the lumber yard I work with provides all kinds of extra services. I have had my representative deliver materials to my site on the back of his pickup truck so that my guys did not have to leave the job site to gather a few “extras.” They do full take-offs from plans. In other words, I give them the plans and they tell me what I need and place it in order batches so that I order the right materials at the right time in the job. They work with lumber companies to provide free engineering documents. That’s a lot of value that could have been missed if I only compared the price of a piece of wood.