I love the Peleton weights. They're not cheap, but they're pretty, easy to hold, and don't hurt my hands. I don't like the way the neoprene covered weights feel in my hands, and I don't like the way the regular steel ones at the gym feel on my hands, either. These weights are perfect!
I think a jump from 12 to 25 pounds would be a tough transition if you are going for any type of repetition. I waited 12 weeks for stupid dumbbells...so my friend told me to get creative. For 20 pounds she suggested a case of soda/bubble water/etc. :-)
I've ordered dumbbells from Amazon. I prefer the neoprene because they are softer to grip and my hands don't sweat. I will say, a jump from 12 to 25 pounds will be very difficult. Just going from 12 to 15 was quite the difference in weight for me.
I have 3, 5, 10, 15, and 20 lb weights and will be purchasing 25 lb. Peloton weights soon. I use all of them regularly and am grateful to have those 10 and 15 pounders to switch between for medium weights for days when I feel stronger or weaker.
If you're looking for just a pair of 20's, I'd recommend trying craigslist or Ebay. A whole set can be expensive (even 2nd hand), but there's a decent chance you can get a single pair of 20's at a decent rate (although the shipping cost on Ebay would be nasty). 12 to 20 is a big jump, but manageable, and much easier than 12 to 25. Definitely get some practice exhausting yourself at 12 (immediately followed by a few reps at a lower weight), to get prepped for 20. Or just buy both 15 and 20 if that's a reasonable/affordable option.
I bought a pair off Amazon. And while they were slightly less than say, Peloton they were GARBAGE. The handle was so WIDE I couldn't grip it! So I did one workout and quickly had to send them back. I think we're going to go with the wise advice of the Peloton brand because they are roughly the same cost and way better quality. I hope this helps someone. This is what I bought.