I'm interested in a composting unit for our mini-garden, but would like to take a look at it before buying and everything of this nature seems to be available  online but not in any shops (tried HomePro, Big C, Verasu, Chatuchak, etc.).

Not much good at DIY, so would like one that is ready-to-use rather than starting from scratch. The ones online range in price from several hundred to 30,000 or more baht, and run the gamut from bokashi bins to high-tech electronic marvels. Would appreciate advice regarding home composting and suggestions of shops/stalls where composters can be purchased. Thanks!

The title states for a condo terrace! Can you supply a picture of the garden you are trying to service with compost? On face value I would suggest you look at buying compost, worm casts even soil in small bags from good suppliers as needed. I doubt you have the space or the volume of soil/plants to justify doing it yourself. 

But if you are intent on trying it, I would suggest a simple worm farm. A simple plastic box which you need to cut a hole in the base and install some plastic fittings to form a drain. Materials to form the bed would be straw, coconut fibre and cow manure. Your kitchen organic wastes put on top. A Kg of compost worms would cost about 1,000 baht. Everything else even less.

Thanks for the advice. Actually, I'm looking for something more ready-to-use as we're totally inept at putting things together and it needs to fit inside the condo. 
You're right about the terrace garden being small. We consume an enormous amount of fruit and vegetables, and thought it would be environmentally friendly to make use of the peelings/remnants. Excess compost would be donated for use in the condo's public garden.

I would suggest a bokashi bin for use inside then. You should be able to source a bin and some bokashi bran or similar to add to the mix on the internet. No smell then. Note bokashi is not the same as compost it is usually buried in a garden.

Thanks again -- your advice is greatly appreciated.