Hello bstrong, if I'm reading your question correctly you are looking for some models of machines that have AC/DC capability and might be reasonably priced. Lincoln makes the AC/DC Idealarc 250, a real workhorse, they also make an AC/DC light duty machine that has 130A DC and 250A AC. Miller has the AC/DC Dialarc 250, they also make a lighter duty machine I believe it is called a Thunderbolt that has 150A DC and 250A AC. There may also be some Airco machines around, I believe the Bumblebee was one of them that was available in a similar format to the two lighter machines that Lincoln and Miller manufactured, they had a heavier duty one that was identical to the Miller Dialarc only painted orange. Century has also manufactured some AC/DC machines that are pretty decent. I know that Fourney made a number of welders but I'm not sure if they had any that were AC/DC, Midstates might also fall into this category. You might run into a brand that was called Sureweld, but likely these would be much larger and more industrially suited machines. Some of the older Linde(Union Carbide) machines might fall into the same category as the Surewelds, as might some of the P&Hs. The main thing about a used welding machine is if it welds well and if it is manufactured by someone that is no longer in business make sure that you buy it very cheaply. Good luck and regards, aevald