The first thing I look at is the blower. If they are turning freely with no hit of broken teeth, you're good.
After that, I want to know that the ash gate on the bottom is free to move, as well. A lot of times they are rusted in place and you'll have to break them loose.
If all the joints are solid and the blower turns freely, then either of those forges are golden and worth the money. I particularly like the first one as I've never seen one with a supporting leg for the blower. That will take a lot of stress off of the cast iron mounting points.... which just happen to be the points of failure for most forges. That the blower is also larger is a definite plus, too.
Assuming that everything works, all you would need to do is add a fire cement liner to the cast iron pan to form a fire pot and prevent differential heating that might crack the cast iron. You can make a "cement" liner with 3 parts cheap kitty litter (pure clay) to 1 part sand and 1 part wood ashes. Works good if you don't have access to the real deal. You can also substitute portland cement for the kitty litter.
Form the cement so you have a bowl in the center to concentrate the coals. You should have about a 1" lip around the perimeter when done (to contain the fuel) and a fire pot thats somewhere between 8" and 11" in diameter, depending on the size of the pan and your needs. Note: let the cement dry for several days and then start a small fire in it to further dry the cement. Go too hot too soon and you'll cause some serious cracks that defeat the purpose.
Either way, I wouldn't hesitate to spend three bills on those forges. Try to talk them down if you can, but don't think you're getting a bad deal if they won't budge.
