Can bachmann cars of all types be labled with your favorite line on them before being shipped to you?
Bachmann's rolling stock is all manufactured and lettered in China in set production runs. It would be economically unfeasible for them to custom letter them per a customer's order. If you need something that is not offered in mass quantity, your best bet would be to repaint and reletter for your favorite road.
Last time I looked into something like this (+5 years ago) if memory serves, the cost was about 7500USD for 300 cars minimum, with 3 color print. Unit cost was about 25 bucks. All cars were to be the same boxcars.
That was from a competitor and years ago.
If you could get it done in China, that might help on cost. But that's a big if.
Good luck