Athearn still lists the EMD SW7 Cow and Calf on their website.  Whether or not you can find them for sale(the few discount model railroad suppliers list them as not in stock)could be a challenge - especially if you have a road preference.

In HO Scale:
Stewart (Now Bowser) lists FT, F3, F7 and F9 locomotives.
Intermountain lists FT, F3, F7, FP7, & FP9
Athearn lists F7
Athearn Genesis lists F2, F3, F7, and F9
BLI/PCM lists the F3 & F7 and E3, E6, E7, E8, & E9
Walthers/P2k lists the F7, E3, E6, E7, E8, & E9
Walthers/P1K lists the F3
BLI/PCM may produce the Sharknose
Model Power used to produce the Sharknose
E-R Models used to produce the Sharknose
MRC used to list an F7

(The Bachmann Sharknose appears to be a repackaged E-R Models Sharknose.)

And I'm sure there are a few more out there,including brass.

Don
Lower Arizona