On my tank of roughly that size im running 2x 30W 6500K bulbs which do well enough - im quite heavily planted though.
In terms of wattage and how many bulbs needed it really depends what your trying to do with it e.g. light/heavily planted tank or bare etc, doubles are more expensive but more worth it if your looking to add more light, for that size theyre usually 90-110 for a double hood.
Personally id go for the highest wattage double i could find on there, T5's aren't up on trademe that often and cost more, alternatively you could look into building your own if you wanted something more specific.
Also ive found that going to a lighting wholesaler or hardware store saves quite a bit on bulbs compared to a pet store in my experience and you can get more specifics for wattage, kelvin etc.
Hope that helps