I have a nice townhome rental that rents for $1550 per month.  The rental market in this area is very seasonal being very hot April-September and cold from October-March. Last June I listed it and had multiple offers and ended up accepting a young couple with good jobs and credit. They signed a 12 month lease. They seemed ideal, they paid rent early and kept the place reasonably clean.  Four months into the 12 month lease they called and said they were interested in looking for a house in the area.  I told them they were responsible for the rent for the duration of the lease, but that I would relist it as soon as they told me they gave me a move out date.  I explained the seasonal nature of the rental market as well.  They called at the end of October to and told me they were under contract for a house with a move-out date in early December.  I listed it that day, but had no showings during the holiday period, which is not unusual and sporadic showings since.  He paid rent in December and January, but is refusing to pay rent for this month because his new house expenses are too much.  It turns out his new house is $573,000 so I have a hard time feeling too sorry for him.  I plan to pursue the rent he owes me. He has 4 months left on the lease so at most $6200. 

I have one months security deposit and no damage to the unit that will go toward unpaid rent.

I have 2 questions.

1) Should I pursue this in small claims court or engage an attorney.

2) Do I pursue the late rent amount each month or pursue the entire amount after the lease ends at the end of May or when a new tenant moves in whichever occurs first.

Any first hand advice is especially appreciated.