Rizwan,
Although our recent purchase is not in Sydney the buying/research process is the same ....
We've just bought a 1 bed flat/unit in Queanbeyan about 9km from Canberra CBD for under $120k, .... we have a tenant paying $140pw and with a basic reno (paint, carpet, bathroom tiles and freshen up kitchen - max of $10k budget) we should be able to get the rent up to the $180 mark.
It probably won't grow at the same rate as a 2 bedroom, but at the price we paid and it's close proximity to employment, the CBD, transport combined with the chronic rental shortage in the region I believe we will do okay. I can only see upside on this one.
I suppose I'm saying that although I'm not a big fan of unit's (I hate b/corp costs), if the deal stacks up with the purchase cost, location and yield and it's what you can comfortably afford them why not? It really comes down to personal preference and your expectation's of what you want from the investment.
Oh yeah ... get to know the market area well, get a genuine feel for the market value and see if you can grab one that you believe is undervalued, ... this will only happen by spending many hours studying the intended area and negotiating hard.
Speak to property managers (not sales agents) in the area, ask them what rents well, what features tenants are looking for .. e.g. secure car parking, security, transport etc And then base your search around that information ..... buy what is in demand and you will have no problems attracting tenants and commanding top rent.
Good luck with your intended purchase ...
Martin