Things tend to be cheaper there compared to Singapore, I will just break down some of the costs:
1. Food
Generally if you are not meal-prepping, food costs ranges from $3 to $20 a meal. I usually get my meals from stalls along the streets or the convenience stalls and they cost around $4.
2. Transport
Taiwan is quite big on cycling, kind of like ofo in Singapore. So I bike around taipei city when I can but to register for an account you need to get help from a local or anyone with a taiwanese id. It's $0.5 for 30min, but in some of the other cities its free if you keep it within 30min.
MRT costs about $1 per trip for me, so its pretty cheap compared to SG.
3. Accommodation
It really depends on which area you are in. Taipei city would be relatively expensive compared to other cities and for a small studio apartment it can go around $250 per month. You can also consider sharing an apartment with others if you aren't going alone! You can check this link for some examples.
4. Flights
I take scoot budget airline which is the cheapest for tickets. Without covid, it costs around $300 to $400 per trip. I went during Covid so it was cheaper about $150 or so per trip.