Tough choice, especially considering the D90 is still more expensive where you are (its actually cheaper than a D5100 in the USA). D90 is typically considered more of a 'prosumer' model and the D5100 would be perhap, 'high end consumer', but they're from different generations - so things get interesting.

• The D90 offers a more professional body with more external controls, a in-body focus motor, and a larger, brighter viewfinder.

• The D5100 has a newer, better sensor (especially in low light), better video mode, higher resolution, and an articulating LCD.

• The pure image quality of the D5100 is much better than the D90, especially at low light, but the D90 is easier to operate and use in the long run.

• If you're planning on doing any video, I'd probably go ahead and get the D5100 since its more geared for that.

• If lens price is going to be a big factor, the D90 has an inbody focus motor which will allow you to autofocus with AF lenses instead of just AF-S lenses - MUCH cheaper to buy AF lenses, but they're slower on autofocus.

Only you can decide if the points above make it 'worth it' or not to you.