Hi Sean, and welcome to the forum!
If you want to head down the Biker Scout path, then a great way to start is a black Imperial Crewman outfit.
Here are the costume requirements according to the 501st:http://www.501st.com/databank/Costuming ... ridge_crew
You'll want to join the Imperial Officer Corps for the details on where to source all the items for the outfit:http://www.imperialofficer.com/forum/
The reason that the Imperial Crewman is a great starting point is because it is a gateway outfit that can be used to get your feet wet with Star Wars costuming and get 501st approval. Also, it's not a major financial commitment.
When you're ready to move up to the Biker Scout, the jumpsuit will be your base under the armor. You can work on slowly collecting parts for the scout while still trooping as a crewman. Go to the Pathfinders Detachment to dig into the details of the Biker Scout:http://forum.bikerscout.net
Or, you could change your mind and go for a TIE pilot. You'd just need to add the helmet, armor, chest box and hoses and ta-da, you're ready to dodge asteroids!
Or just add a beetle helmet, and now you're a Death Star gunner, ready to pull the lever making the really cool "beeeowww" sound!
Or add the Naval Trooper helmet with a blaster, and you're ready for Detention Block duty!
Although the Imperial Crewman is not a glamorous, readily identified and recognized outfit, it is a great start to Star Wars costuming, and gets your foot in the door. A whole world of opportunity opens once you're approved as a member of the 501st.