Don't ask for "marrow" ask for beef shanks and femur bones. Once you get them ask the butcher to cut them up on the saw.
Yellow pages says this is the closest Meat market to you. Give them a call and see what they say.
Regier's Custom Processing
201 S Spring St
Caney, KS 67333
(620) 879-5177
http://www.yellowpages.com/caney-ks/...?lid=452521343
This popped up on google too. first page...
http://www.ksda.gov/includes/documen...ion/custom.pdf
Cheers