You need to find the gearset you can afford to use. The point of upkeep is that you can't run around in plate armor all the time.
I use medium mail sets on all my characters, making the total cost 25-35k. I make a steady flow of gold with this and can then buy some awshum high-end gear and occasionally use them.
Of course if your goal is to just gain gold (what for, if not gear upkeep?), it makes sense to use cheap gear. On the other hand, is running around in peasant gear 9 rounds out of 10 to be able to play one round in full plate actually fun? I don't think so, but obviously you don't have to agree.
From what I'm seeing so far armor matters little. I'm still new, but I'd say 80% of my deaths have been attributed to players with beef-bus characters (or I'm guessing they're at the cap considering they can swing a two-handed mallet twice before I can even finish one of my attacks). And aside from being beef buses, they're also running around with the best equipment. So I'm guessing you're pretty much at a disparity while leveling up, having to trade off good armor just so you can gain some money, until you're level cap when you're practically gods and you don't have to worry about repairs because you usually survive the rounds.
And isn't being decked out in plate armor a penalty in itself, i.e. weight and speed?