Jak,
If you're just starting out, here's a couple of low cost suggestions:
1) Industrial suppliers sell U-Channel conduit guide (like the stuff you see running up the sides of buildings or big power poles). Its plastic so it grinds well, it lays flat on the ground (Top of the U shape facing down) and its cheap (less than $10 for a ten foot section). Get the 6" wide size for rigidity.
2) Salvage yards sell reclaimed iron fire sprinkler pipe. Its tough, grinds great and with a couple of cinder blocks you have your own adjustable training rail. Most of the Soap demo rails were made out of this stuff in the 3" diameter size, welded to square channel legs.

Jak just buy a long peice of PVC pipe thats what I did long ago and I use it all the time it works great.

BTW Go2Crew
Are you a ebay seller?

ummm i agree with what go2crew said....except, put something on or around it so that it doesnt roll away....those plastic pipes are REALLy fun to grind

Oh I was just wondering. Because I thought your the one who sold soaps to my brother.