Alrigt, i like WW II theme.
Yes the modeling using reference is the best way, modeling without is is impossible (tecnically it is posible but it will take you 10 times more time and you should be really skilled to make it look good).
You dont really have to pay for reference images. there are some cool sites
best blueprints, mostly cars but you can find some characters to:
http://www.suurland.com
http://www.the-blueprints.com
anatomical reference, i really saw a ww2 soldier there somewhere:
http://www.3d.sk
You can use some images as a reference(the images are originaly made to display their products)
www.turbosquid.com
And many times it can even work with google image search (or sometimes net search)