Actually, the HG37 pictured is a step up, about twice the cost and has chrome cogs versus brown and black. But it should do fine.

The freewheel I refering to is the MF-TZ07. I don't have the 2009 shop catalog at home, but the 2008 catalog shows a retail price of only $9.00 and that's $CDN, so I can't imagine the 2009 US price being much over $10.00. Should be available though your LBS.

I use the 6 speed version regularly, as a replacement for all the freewheel failures on the department store bicycles that come into the shop and years I have yet to receive any complaints or returns.