Hi,

I am using a LM358 with a "K" type thermocouple and a LM34 for reference temperature.

I get the thermocouples from omega.com.
http://www.omega.com/ppt/pptsc.asp?r...TXL&Nav=tema07
Is the one I am using but these are nice and in your price range
http://www.omega.com/pptst/WT.html

But if 450 is all the higher you need, a "K" is overkill "T" will go up to 752F and one of the leads is copper. This helps with reference connection problems.

When you pick your PIC, get one with a 10 bit ADC and enough program memory for the look-up tables.