To learn, there are a lot of resources available on the internet for free. There are some courses listen on SkillsFuture for Arduino stuff but it seems really pointless to spend $450 and up for something that can be found online. The Arduino website itself offers a range of tutorials focussing on different areas. If you'd still prefer to follow a (free) course to get the basics these three look pretty good (haven't followed them myself):
If you come across any issues that you cannot solve based on the learning resources and/or Googling you can ask (for software and hardware issues) on the Arduino forum or (for software issues) /r/learnprogramming. From what I've seen of these forums people are generally polite and helpful (also to beginners).
To buy Arduinos and some electronic components for prototyping/testing at a reasonable price I would recommend AliExpress. I'm not sure how the prices compare to Sim Lim but definitely a fraction of the cost of the official Arduinos. I've never had an issue with a product purchased from here not working, the main disadvantage is that postage takes a long time usually.
I'd love to recommend some specific tutorials for you, but I would have to know in a bit more detail what you're hoping to achieve. Is it to get the keys that you press to light up, or something different/more complex? Also it would be good to know if you have any programming or electronics background at all?