So, you need to ask yourself "why"? Where are you playing that you need both competitive and Budget AND can get you on the path for upgrades?

Is it for fun with friends? Just proxy. Is it for fun at your LGS? Proxy or get ultra budget while you work to build a full t1/2 deck. Is it at your LGS FNM Modern tournament? Unless you're bringing true t1/2 you'll get creamed anyway, so don't worry that much about "competitive" and simply have fun playing magic.

Jump on Xmage or proxy with friends, play around with a few decks and see what you really like. Don't buy into an archtype because it's budget and upgradable only to regret it 1-2 years from now.