Usually their Members Special is good px, also for minifigure, keychains, magnet sets.
For the rest of Lego sets, you must know the HK$ and US$ px well to compare. (I usually go to their website and check px, then prepare an excel table to compare the px of those sets which I like first, then buy online and collect when I am in Singapore.)
I get 10% discount on ordinary px items, (no further discount on special px items), then if one buys over SGD100 can ask the shop to prepare for forms so that you can claim back some GST at the airport, usually can claim ~4% - 5% back.
** Can also claim GST from purchases from Popular Bookshop, a lot of good supplementary ex for English, much cheaper than HK if you don't mind carrying them back. (eg HK$58, if you buy from Sing it is around HK$3x.) But again, must know the HK px before you buy.
There is a "book city" type of building, called Bras Basah Centre, which is right next to Raffles Hotel (the very classical hotel).
eg I went on 17 June, it rained very heavily in Singapore on 16 June, but sunny on 17 June. And it was still Singapore school holiday.
I got my tickets on internet beforehand, so did not worry about it. But when I got there around 11:30am, we found that the USS was already "Full" that day and they did not sell tickets at the entrance.
So I would recommend that if you plan to go, either get there by 10am (opening time), or buy beforehand (but has risk of bad weather).
Yes, HK Popular card can also be used in Sing Popular. Remember you can also claim GST if you buy S$100 in Popular, and ask the Customer Service in Popular to prepare the form for you before you leave the bookshop.
Bras Basah Complex = lots of books and local exam papers. Also has books from Malaysia (much cheaper than Sing version). But not too many story books and chapter books in that popular. Actually if you want to buy supplementary exercises like me, esp in English and Maths, you should go to the Popular bookshops in the local housing estates, cos more kids ==> more demand.
There is also a Popupar bookshop just outside (underneath) the Jurong East MRT station, this station is the closest one to the Science Centre, within 10mins walking distance. You can even buy space astronaut food (ice cream !) from the shop in the Sc Centre.
If you like the brand "GAP", you should go to Orchard Road - Wisma Atria or to Vivo City (Harbourfront MRT), I bought some T-shirts, less 50% and a further 20% discount if you buy 5 items or more !!
(I like shopping you see !)
If you need help with buying Lego, just pm me and I'll see if I can help. You can just go to the shop and buy there. But do check the price first.
I haven't been to Snow City, cos I don't like the idea of wearing wet jackets which a lot of other people wore without washing. And I don't like going to the Bird Park cos of H5N1.