I dont know if it works for your sutuation, but I used pass the parcel and set up their address as the pickup point and my address as the delivery address. All you need is the box dimensions and get them to print out the postage label, as you are paying the bill you know exactly what the postage costs, and they pick up from any old street address. Worked for me when I bought some stuff off trademe and the seller would not post as it was too bulky and would only let me buy it if I arranged the delivery.
If you know what it weighs and dimensions it will give you a quote.
Also of note, it was my first and only time I did that and I had to create an account, but was easy. Cheaper by heaps that going direct through some other courier companies which I tried first.