Look, mining isn't just an "investment", you would be purchasing equipment that you are responsible for and have to run to make a profit.  The only way around this is to pay for hosting somewhere.  In this case, the hosting company would keep your hardware on site, connect it to a pool on your behalf, and pay out to your wallet.  Take a look at KnC, you will find the fees though are actually quite expensive.  You may never actually get an ROI on your investment because difficulty is increasing at a rate of 110% per month right now, rapidly diminishing returns that can't really outlast the cost of expensive hosting.

You do have other options, you can buy BTC, or you can even invest in BTC businesses.  My business partner and I are working on two projects right now.  We have purchased our own mining equipment and identified a commercial location with electric rates at .04/kwh.  This is significantly less than the average .15 to .18 that most americans pay, and in the EU rates can exceed .30/kwh.  We are planning out a data center for a hosting service on this location.  Our rates would be considerably less than most hosting services given that we can pass on the savings to our clients.

The other business involves a billpay service.  The company is CoinChex LLC, site is under development.  I'm spreading my risk all around and investing in multiple aspects of the bitcoin economy.  This is probably the best way to generate ROI and reduce your risk.