Wanderer,
I went here to be sure there is a Walmart near to you:
https://foursquare.com/v/walmart/4e1645d6c65be9c55e8436df
Go here to read about the options:
http://www.wikihow.com/Connect-PC-to-TV
With a bit of search, the basic information about using a TV as a monitor has a couple of significant considerations:
First - Does your portable have a function to use a remote display? Nearly all current models do - it is just a matter of finding the function key or setting panel to activate the remote monitor. Assuming it does, then the next is
Second - deciding on the connection from the PC to the monitor. Once again, it depends on the capabilities of your portable and the TV to be compatible: HDMI to HDMI, USB to USB, VGA to VGA, s-video to s-video, RGB to RGB, All but the first two only transport the picture, so an additional audio cable is needed.
I'm not sure how the local Walmart there has pricing, but you should be able to get a current model HI-Def TV at a reasonable price. My local Walmart store has an RCA 24 inch Hi-Def TV at $149 plus tax.