Quick and cheap conversion option for MTB freebody

[Fisan]

Is there a cheap option (below R200) to get a standard a single-speed cog to fit on a std Shimano MTB freebody (including spacers & lockring) or whatnot to keep it in place.

 

I see Rapide sells a cog for R129, but then I still need some spacers and a lockring. This is only for a temporary conversion....for reasons....so I don't want to spend to much.

 

edit: how do I change topic title...? 

[JanJan]

Best bet is to head to a few cycling shops and ask if you could salvage old worn cassettes and remove their spacers. Your major cost would be fuel and buying the owner(s) a coke.

[Malpiet]

yes, but the initial cost is more, getting the correct length spacers etc is a pain.

[Spoke101]

You can buy spacer kits but the whole lot with sprocket with set you back ±R300