Well if you want to try out a few boards before you settle on buying one, do youself a favour, and buy your own boots. Spend some money on those. Then you wont have to rent boots and worry about other's smelly feet being in them. It's also may be cheaper that way.
As far as used boards go.. depends on how much are looking to spend. If you are looking at something to get you started.. you could probably find a 2 or 3 year old board from Burton for pretty cheap. Or you could go to sport swap or something, and pick up a cheaper albiet newer board for about the same price.
If it is something you are just going to learn on, and throw away the next year, or use a rock board if you continue, you may want to go with option 2. Otherwise, if you think you might stick with it for a while, get a better quality board that will last you a couple years until you are willing to shell out the $800 for the latest and greatest
