Buying properties too fast?

[Mariah Jeffery]

I bought my first duplex in March '07. It's in South Dakota and managed by my father in law. The first one worked out well, so I kept looking for deals, but couldn't find anything that met my cashflow criteria. Finally, this year I found a motivated seller. He is '87 and wants out NOW before he dies. He has 65 properties and will sell be any of them at about 25% below market value. They already have tenants in them and are in good but not great condition. I have bought one per month for the last 3 months (a 3-unit and two 2-units). I just made him an offer on a 4-unit and he said he would accept it if I buy another 2-unit from him at the same time, also at well below market. The 4-unit meets the 2% rule and the 2-unit is at about 1.5%, but is an incredible house in a very nice area, which will attract great tenants. I also met another motivated seller this week and made an offer on two duplexes, which I am waiting to hear back on. Additionally, I found a potentially fantastic deal on an REO fourplex that I want to make an offer on, which would also meet the 2% rule. I'm finding the kind of deals that I only dreamed I would find, but if they all work out, I'll be at 21 units in a few months. This is a big jump from two units! Two units is a hobby and 21 units is a regular small business. Am I setting myself up for failure by growing so fast?