You can make deck blocks out of 2x4 and deck materials. Using treated lumber you simply cut two foot lengths of 2x4 set them on a level surface then cut 2 foot long sections of deck board and fasten them to these two boards. Once done you simply place them together to form your deck. Be sure to keep the 2x4 boards close to edge of the deck so they do not kick up if you stand on the edge past where they are fastened. Need another design, pick them up and move them around. Just be sure your ground is level and your good to go. Nice weekend project. Paint them different colors and create a design all your own.
Great advice from Woodbridge. I saw something awesome on a blog the other day This woman rents - look what she did: http://jennifersmentionables.wordpress.com/2012/05/21/friend-your-mr-furley/
If you have not done this yet, check out Lowes they have all kinds of ideas. No I don't work there! You may need to check local regulations also.