If the Steam Era Freight Car Prototype Modeling community was the economic engine it thinks it is in the hobby, you'd have no problem finding any model you want from this era in any store, hobby shop or museum gift shop. The Walthers catalog would be full of every car you could think of.
I'm sorry folks, but you're not. There aren't enough of you to make economic sense for historical societies to do many of the projects you want to the level of accuracy you want and allow the historical society to make a profit. I wish there were more of you. (The B&ORRHS has done well with several car projects of the steam to transition eras. We do have a strong group of modelers involved in our leadership and that does shape what projects are undertaken. Other groups have evolved along different lines to preserve the history of their railroad.)
Historical Societies are getting to the point where we are going to have to start looking at the MFCL for ideas. Middle age people today do not remember steam. (CSX turns 30 in 3 years.) We aren't hobby shops for any one clique, our job is to educate about the railroad. If that's done via a magazine and/or a museum and retail is just done to keep the lights on, that's it. As a director, if a foobie returns 40% off our investment, I say keep selling it until it stops moving. The models are not necessarily the mission. Some groups make a strong effort to use models to educate and that's super. But don't condemn a group that chooses not to. I don't. I've been through the meetings where we look at income vs expenditures and red ink or the potential for red ink makes for some tough choices.
If that's something that gives you heartburn, I suggest you remember that making accurate models is not an IRS 501c3 requirement. Then take a deep breath, relax and go look at the Barriger Library's Flickr page.