if your company can provide

company tax return form, it is also ok.
my company only provide one year (2004) audit financial statement report(it is 7-10 pages, including a lot of numbers), and free from the company provided statement. we didn't provide tax return form.and TSC passed my I-140.
don't know why they charge so much..never heard about it.
if your prevailing wage is higher than your current pay? I140 mainly check company financial condition to make sure they can pay your prevailing wage amount.

good luck