FWIW I agree with the others that most builders are nice enough to let you keep leftover bricks provided there are not heaps of them and provided you also move them out of the way for the site clean.
I moved mine with a wheelbarrow and the help of some friends/family just after bricking was completed. A couple of tips; firstly wear some good gloves so as to avoid sore hands, secondly stack the bricks on some pieces of wood/metal so they don't sink into the ground too much, thirdly put them in a vacant area where they won't be in your way as they may sit there for some time! Finally try to stack them in rows of 50 so you can easily count how many you have, also stack the couple of bricks on the end of each row in a different direction to the rest of the row so your pile is nice and stable.
Good luck
Thanks for the great tips!!! love your work.