Welcome to Cloud City!
There's several costumes that fit various body types, and of course various price ranges. We've got a great group of folks here who can point you in the right direction for any costume you might be interested in. For example, Imperial Crew uniforms fit any body type, and can be easily converted to Gunners or TIE Pilots. The base uniform is also one of the less expensive costumes to pursue if that's a concern.
A good place to start is the 501st.com list of detachment web sites. Those forums are specific to certain costume types, and filled with all sorts of knowledge of the costumes and what it takes to build them.