Need help researching rarity of a loco

I don't think I've ever seen a UP 4-8-4 Bachmann (which doesn't mean they don't exist), so I would say it's somewhat rare......but  it probably has no more value than your run of the mill Bachmann Northern. Bachmann products are not noted for their "value" regardless , so even if it IS a factory release, I doubt there is any added value to the UP version. It's also possible that the UP version is from the very early releases of the Northern, which were of noticably lower quality than the new versions, which aren't that great either. I don't know how you plan to sell the locos, but if you plan to use that auction site, I'd start with the price you see for other Northerns and let the bidding take care of the rest.

I just looked, and there is a UP Bachmann 4-8-4 on ebay....it is in the old cardboard box, so it definitely is an older model. Current price is $42 with 4 days left. It's a nice looking engine. You can pick up brand new Bachmann Northerns for $60

Here are two for sale:

http://tinyurl.com/5b5nk2

http://cgi.ebay.com/029-Bachmann-Union-Pacific-4-8-4-Steam-N-Scale-MINT-NIB_W0QQitemZ290242133288QQihZ019QQcategoryZ19122QQssPageNameZWDVWQQrdZ1QQcmdZViewItem 

http://tinyurl.com/636tvn

http://cgi.ebay.com/Bachmann-4-8-4-Union-Pacific-loco-engine-N-gauge-lot_W0QQitemZ180259770292QQihZ008QQcategoryZ19122QQssPageNameZWDVWQQrdZ1QQcmdZViewItem 

Maybe this will help.......

http://www.visi.com/~spookshow/bach484.html

If you have questions on N scale loco's, this encyclopedia is a great place to start: http://www.visi.com/~spookshow/locos.html

Personally, I have several of these loco's from different eras.  The old ones are not so hot most of the time.  The new ones can be made into excellent performers.