I don't think investing money into 1 miner will be profitable, a month back when I was doing research for a mini rig of myself, I realized it would very unlikely to make any profit from mining in a pool unless you have a large range of miners.
It might not be extremely profitable, but if he connects to a pool that generates a decent number of blocks per day, and keeps the cost of running low, he may be getting a marginal profit which for most people probably isn't worth it, but for OP it might be. Some people mine to hold for a longer period of time because they expect a significant increase and don't mind the lower initial rewards.
The thing that people who are starting with mining tend to underestimate is how they don't factor in how hard the difficulty can increase, and that over the long term, it has always a bias to the up side. If you keep running the same one or two miners without adding any new miners, it's going to be a penny game that you will lose.