Maybe the most impressive diy electronics paradise in Singapore is a tiny, well hidden shop in People's Park Center, 101 Upper Cross Street, Suite #03-06, near the Financial district and in walking distance of the tourist hubs Funan Center and Clarke Quay. Rather small in size, I am perfectly confident to say that not one other shop in the world has reached this packing density.
This shop definitely dwarfs the big European component retailers, such as Conrad with its variety of goods in stock plus delivers the same at fair prices. Amongst the treasures to be found are NOS tubes for Audio and RF amplifiers, a selection of high quality japanese ALPS potentiometers such as the legendary "Blue Velvet", Antennas for every thinkable transistor radio, high end grade audio capacitors, a vast variety of LCD and LED displays, switches, plugs, sockets, adapters, fuses and many many things that had to succumb in the bow to the mass market in most western countries.
The goods are of excellent quality, the shop is run by extraordinarily friendly and knowledgeable owners. You might want to request some help from the owners as navigation in between the tightly packed shelves is rather a matter of orientation and experience. Component prices are attractive and fair, Test equipment is available too, prices for that however do range above the same found in the well known surplus outlets in Europe and America and dragging heavy things back will probably not be much of an attractive option (Remember that Singapore has a very vivid second and third market so prices for used equipment will be higher than somewhere else).
Of course there might be specialized items on your shopping list which might be better found in a highly specialized shop but for general requirements this one shop beats all of Sim Lim Tower (the main components hub) hands down. Rating: A clear 5 out of 5. If I had one electronics shop I would want to take with me to a deserted island, this would be it!