You're a good shopper......

Heh, those prices were off the top of my head. I bought and built this thing over a year ago. And I didn't include shipping on anything.

Were there different versions of the 75mm? That barrel looks rather long. Maybe it's a perspective thing...

There were 2 different 75s. The M2 and M3, early tanks had the shorter M2 guns, sometimes seen with a counter weight since there was a shortage of M3 guns during production.

3 versions actually.

Early = shorter M2 barrel with no counter weight. (commonly seen in training in Kentucky, and British Grants)

Mid = same short M2 barrel with a counterweight. The counterweight was added when stabilization was added. (commonly seen on Grants and the Lees in North Africa)

Late = longer M3 barrel, which basically replaced the counterweight with a longer barrel, which also added some additional velocity. This was the same early barrel that Shermans received. (commonly seen both in the Lees in North Africa, and the later training tanks in England)