adam01

Recipes 

Get a piece of 'Greenfield' Its a wound metal tube that is flexible and used for
covering wire. You can get a short piece and run it in the wall or outside.

I would get wire sized for the 50 amp circuit. No change necessary if you
go from 30 to 50 amp. Wire difference is small compared to doing it over again.

You can use separate wire - that's what was used before romex (along with conduit.)
Need 3 wires.

clearwaterbrewer

Recipes 

If you EVER think you will want 120V from whatever is plugged into the outlet, you want to get 4-wire... 6/3 NMB w/Ground is worth the few pennies more. here is the 50' at HD, you only need 4', so probably $8-12 http://www.homedepot.com/h_d1/N-5yc1v/R-202206572/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

and a 125/250V dryer outlet (google: nema 14-50 outlet)

You will never have any regrets if you do it this way, and all new installations of dryers and ranges are required to be this way by code..