Additionally,

Overscan is one of those issues that savvy retail people bring up to distinguish between cheap TV's and high quality ones. Your very high end sets will often have overscan ratings of 2-3%, where as cheap sets can overscan to 12-15% or even worse. Seeing as you have one of those "off brand" sets (Orion) you are pretty much stuck with massive overscan. In fact, your question:
"can you recommend some relatively cheap TVs that let you adjust the screen width and height?",
Is very easy to answer. The cheaper the set, the more the overscan, the less you can fix it. Spend a little more money on a recognized brand name (and not the entry level model) and you'll not worry about overscan again.

Jeff