Raised bed ideas

Scott and I have been planning on making some raised beds for our garden this year. We went over a few ideas of what materials to use. Railroad ties, corrugated fiberglass sheets, treated lumber, scrap lumber, etc. First off, let me say that Scott doesn't want to be bending down to pick weeds, so if we have to make 4ft tall raised beds in order for him to share the weeding burdens, let us build a wall!!! So price wise, the RR ties and fiberglass sheets were approximately the same. About $100 for a bed measuring 4' tall and 4'x8' in dimensions. We want something that isn't going to basically rot in a few years. But being that we are still working on the downstairs of our house, we need to save where we can. So we figured we could build a bed out of scrap lumber now, and make it slightly smaller so in a few years, when it begins to rot away, we can just build one out of RR ties around it and not have to deal with the mess. The lumber will basically compost into the garden. Not a terrible idea, hopefully it pans out for us! :) Pictures to come.