Pamm,
depends how cheap is cheap to you. For aircon, if you are interested, pm me. The uncle that service aircon for me charged $20 per unit. Total $60 for the split unit. This is the bargained pricing.
Some things that you should at least do:-
1) Change the locks.
2) Grease all windows and doors hinges. Check that the screws are secure.
3) Check the signal strength of your SCV point. You can use the setup box itself to measure the signal.
4) Complete cleaning and disinfecting.
5) Clear all drains and basin waste traps. If its simple choke, go to h/w shop to buy a device to clear the choke, costs only $6-10 for 3-5m long.
6) If old estate, check the rubbish chute is good and not leaking. You might want to replace one with a air-tight smell proof one.
7) Walls, check for any peeling and do some touch-ups. Its really easy nowadays as h/w shops can get you the exact color regardless of brand. Also, look out for mouldy parts. Most paints can be washed. Just use a bit of detergent with a pail of water to clean walls that are dusty or stained.
8) Check all lightings. Change old bulbs to energy saving ones. For florescent, make sure the starter is good and its not blinking or the tube slightly burn-out.
9) Check the water heater. Let it heat up about an hour and waste some electricity there. The main thing is to ensure the pressure valve is working. If it isn't, you will have hot water spilling over very quickly.
10) Check the water quality. If the piping is old, it could be rusty. Then, you might need to purchase some water filter or purifier.
11) Look out for pests. Lizard shit or cockroach eggs and spider webs. Then, get the right anti-pest baits.
12) For all the cabinets and drawers, you might want to buy rubber sheets sold in Ikea. Cut into the right sizes for them.