Hi,
Thanks for the feedback. From your view, i guess i will go for u3 secondhand:) Yeah i am planning to complete my diploma, but of course i have to go grade by grade from the grade i stopped.....unless i am supergenius can jump from grade 5 to diploma 
Dreamaurora:flyindolphin:Hi,
What actually sostenuto pedal is and what brand of piano that have this type of pedal, budget range $3-4k. Thanks.
A sostenuto pedal sustains notes without lifting the damper mechanism, allowing notes to be played above the sustained notes without blurring them as what will happen if you use the damper pedal. Most modern grand pianos and some upright grand models such as Yamaha YUS5 and Kawai K8 have them.
It is a common misconception propagated by many piano salesman that you need a sostenuto pedal for diploma. In practice, it is almost never used at all. Sostenuto pedal is a relatively new invention and most pianos from early 20th century do not have them at all. And as such very very few pieces actually specify the usage of sostenuto pedal. A good regulated U3 or K7 would be sufficient for diploma level. My suggestion would be to get a 2nd hand U3, although you might want to increase your budget a bit. Anyway, am I reading this right? You plan to take diploma after passing your grade 5 practical?