This investment really depends on the level of playing skill you have. If you are a beginner, perhaps it is somewhat of a good idea. But if you are intermediate-advanced, or are contemplating to go "all the way" in music (say, to ARCT (gr11) level to (semi)-professional), i would recommend a grand piano. Perhaps, not too big, say 5'6" or so, if money is tight. It is worth the investment, as you can sell a better piano at a closer price to the original price you bought it at.
Steinway pianos depreciate a lot at the end of its career (as you mentioned it is bright). There are Steinway 7' and 9' Grand Pianos that I play at the University, and they are getting old and in the past few years, have had an exponential depreciation level. You mention that it is over 20 years old, and should look at getting one at the most 10 years old. It also depends on the previous user.
How trustworthy is this dealer? Many dealers can be like second-hand car salesmen. The poor hammerheads are a bad idea. To replace the heads, it can cost $700 CAD ($882.72 SGD). The brillant sound is also a major pain that I experienced with older Steinways. Dealers should repair it first then sell it, rather than sell you a shabby piano then offer to fix it up.
Steinway pianos only have a 5 year warranty. They are good for that period, and longer with lots of tender loving care, but they do have that tendency to depreciate.
I would definately recommend a baby grand or grand piano, perhaps from Yamaha. They last long and are an excellent investment. They are made not too far from Singapore, so shipping won't be as high as it is here in Canada. Perhaps, if you find a good second-hand Yamaha, it will be wiser to choose that than the Steinway.
Good luck and happy hunting!
Topic: Steinway Model V-132