Craftsman volt meter for a pyrometer?

[Railrider1920]

Took a walk in the tool section of sears tonight. They have a volt meter there that comes with a thermocouple. On the package it states that it will read temps up to 1800 deg F.If I'm going to spend about $70 to $90 for a pyrometer, I figured why not get a multimeter that takes temps too. The price is better too. Below are links to the item and the users manual. The temp chart is on page 7

I probably won't be going the route of the automated PID controller. I was thinking of just a pyrometer. So what are your opinions of using a volt meter like this one for taking temps inside the forge?
Thanks

Item
http://www.sears.com/shc/s/p_10153_12605_03482175000P?prdNo=2

Users manual, temps on page 7
http://c.sears.com/assets/own/03482175e.pdf

 

[Stacy E. Apelt - Bladesmith]

Just a point to consider....
the allowed variance works out to a 90 degree swing at 1500F. That will be a bit tough if you are trying to keep a 1450 HT zeroed in. It could be 1405 or 1495, but the meter could say 1450.

 

[Railrider1920]

Thanks Stacey,
That makes sense.
I read the PID sticky a while back. Probably need to do it again. If I was to get a PID device off of fleabay like one of the ones pictured below, get a correct thermocouple to connect to it and I guess a power supply, would that be the basics to make a pid into a "pyrometer"? Or is it more involved than that? I'm trying to get a device that will tell me the temp in the forge, but do it fairly inexpensively. Or should I just look more towards a full flege pyrometer?
Thanks