I got your plans online as I always wanted to build a small, simple greenhouse - these plans were excellent, easy to follow and the job went way quicker than I thought. I did the work myself, so, even though 2 people would have really helped, some judicious use of clamps did the job.
I used deck blocks and standard deck flooring. This raised the structure up, as the low lying ground has a tendency to flood in the spring melt and I used old metal baseboards and leftover flashing to fasten a metal skirt to the structure to keep animals out. A bit of spaypaint to match the metal to the gravel. The wire shelving was inexpensive and I managed to get all of it from a local Habitat for Humanity store. The door I made from leftover wood from another project and some leftover cuts from the metal siding. I didn't need any special tools, but did use the project as an excuse to buy a Kreg Jig, which turned out to be really useful.