Well, rares are supposed to be hard to get; I think the difficulty is about right. It's also not too hard to beat at least bronze unupped. As an example, on Saturday I made some decks for the weekly tournament. (which I didn't play in because I decided sleep > 2am tourney :p) I tested the one I felt was best in pvp1 and also in the bronze arena. In the bronze arena, my fully unupped deck using no rares except 2 arsenics and no odd casting cost cards or odd numbers of cards (the tourney format last week) won the first five games I played in bronze, and narrowly lost the 6th.
What I'm saying is that even someone with zero upgraded cards can do well in bronze, if they know what they're doing. (for the record, the deck was 6 nova 4 quantum pillar 2 lightning 2 fog shield 2 steal 2 nightmare 2 arsenic 2 basilisk blood 2 lycanthrope 2 graviton fire eater 2 forest spirit 2 reverse time, mark of darkness) Even that deck can obviously be optimized for the arena; I mean heck, it doesn't even use graboid, since that was banned in the tourney :p I think going to farm silver or higher fully unupped would be pretty hard, but bronze is completely reasonable.