Hi, I'm very interested in getting pico, and I see that last year was on a sale in a bundle, so my question is.
does pico8 usually have this kind of discount? or is it something very unusual that can't happen again?

I think the discount is unusual happen,i bought it in normal price

I don't think it's likely to go on sale any time soon. For fifteen dollars, though, it's an amazing value.

If you're talking about the Bundle for Racial Justice and Equality, I think that was probably a one-off thing - it was specifically a charity bundle raising money to fight anti-black racism in the USA, not a sale to promote any of the items in the bundle.

As to whether it's worth US$15 ... I think if you like the aesthetic of the PICO-8 carts you've played and you can spare US$15 for a one-off purchase, it's worth a shot - Lua is pretty beginner-friendly, the official PICO-8 manual is clear and moderately thorough, there are a lot of zines and video tutorials to get you started finding your way around the UI (I recommend the "Game Development with PICO-8" zine), it runs well on even low-end hardware, and it has built-in exporters to windows, mac, linux, raspberry pi, and web, which makes it quite easy to share.

I'd say the most non-obvious stumbling-block is zep's philosophy of "solving basic computer-science problems is fun and gluing together libraries is not". If figuring out how to draw a triangle scanline by scanline, or how to sort a table of entries, or how to calculate a natural logarithm sounds like a bad time, then it might not be the tool for you; if those sound like a good time, you might have a lot of fun with this.

...for the record: before getting PICO-8, I would definitely recommend looking at Voxatron, Lexaloffle's other big fantasy console project, because for US$15 you get PICO-8 but for US$20 you get PICO-8 and Voxatron. I didn't get Voxatron because I didn't like the voxel aesthetic - it wasn't worth it to spend an extra five bucks to get something I didn't want - but definitely look at that one if you're thinking about PICO-8, because it just makes sense to get them both at once.