Hi Johare12,
Congratulations on landing, must be a relief now its all over!
We live downtown and yes, its expensive but we love it. Someone mentioned before about Yonge and Eglinton (i work here) and this area has become very expensive, but its very upcoming (yonge and eligible they call it!). Little italy is more affordable, and a fab location too. Probably the cheapest area downtown is the beaches which is nice too. I would avoid Scarborough as it is actually quite far, you can't beat living downtown. Also, if your boyfriend commutes (mine will be too, out of Toronto) Yonge and Sheppard is a great area. Its very upcoming, lots of restaurants, movie theatre etc and VERY affordable compared to else where is Toronto. Its right on the subway line, you could be at union station in 15 mins and also right by the 401 so great for commuting.
Although Vaughan/Markham/Scarborough etc is cheaper, if you want to be downtown you will enjoy it so much you won't regret it.
So i'd check out Yonge/Sheppard (lots of condos) and the beaches (more house style apartments - obviously much more space!).
Good luck and feel free to message me if you need any more info!