You should always price as if it is the "only" property you have in that area. That is where you "make" your money over time as the properties build in that one area.
The first property you take on should take into account the cleaning time, the fuel etc etc. Then as you build the area your fuel costs etc are already paid for by property number one.
So for a standard 3 bed semi with conny (whatever standard may be?

They are all different round here) Say you charge £15 for the first one in the area, for example after fuel etc you actually make £6.00 profit. Then you take on 4 more in that same road that are exactly the same as the first so you charge them £15.00 each. You've already paid the fuel costs etc on the first one, so your profit margin on the latter 4 will be higher. Never ever price lower because you already have some in that road. It will do you no good in the long run and these custies may just talk to each other and you may just lose all of them or have to reduce prices for some!
As for undercutting, there will always be someone who charges less than you and who charges more than you. The time to worry is when someone who charges more than you starts to take your custies!
