Why was 4130 the initial choice? 4130 is usually heat treated (quenched & tempered) to obtain desired mechanical properties for bolting. Welding on it will affect the properties, but it could still be acceptable depending on the application. If 304 is also acceptable, you would make fabrication much easier by using 304 for both stud and tube. Carbon steel studs may also be worth looking at if cost is the primary factor, and not strength or corrosion resistance.
Marty