I'd personally not go with a sliding door on anything I wanted to be even semi air/water tight or use year around or not have dust blowing in a clean room like you mentioned. I have two sliders, one in a barn and one in an unfinished garage that I store seasonal equipment in along with my Land Cruiser. Both face the north and the floors get wet every time a heavy rain or snow occurs with wind. A lack of a real footer under the door makes the problem even worse which also yields them inoperable 2+ months out of the year when the ground freezes and jams the door up into the rollers. I completely understand about wanting to save money but doors are not one area you want to cut corners on. If anything the "finish work" can always be put off until you have the money, electrical, insulation, etc. Things that can be pushed on down the road once the initial structure is up.