If you really want to get into mining and don't have a lot of BTC I would go with CEX.

I use CEX and its a GH (gigahash, aka mining power) trading platform. Market prices are paid for GH, a lot of helpful people in the chat box there and it's really catching on. I have about 8GH on there at the moment and I trade pretty frequently.

The trading allows you to trade up to more GH as the price drops (as the difficulty goes up the GH produce less BTC) but since it is a falling market and still has some upside swings, it's pretty easy to get the hang of, and of course you can just buy and mine and keep mining if you expect the next difficulty change to be less difficult to mine, or if you expect BTC prices to get to 10k within a few months.

I have been able to increase BTC and GHs by trading pretty much flat and buying in lower (you keep the BTC you mine while you wait for your exit point)

The best thing though, is that the GH are yours forever. (unless they go out of business I assume) you pay a percentage for electricity and maintenance.

you can get started with .000001 BTC

the link is in my signature (oh yeah you make a small bonus on referrals to)

Alternatively, you can just buy 1GH for about $11 for 1 year from butterflylabs.com no idea when they will start mining for you, but it's another low-cost option and they take USD

Its better to not waste potential investment money just buying hardware because you want to. Wait for a good opportunity and jump on it, usb block erupters are not one of those. Also you dont need any minimum amount for pooled mining, that's the whole point of pooled mining...