What's the general consensus on this? Better buy at 155$ because it won't go any lower ever again?
I don't think there is a general consensus, right now.
Here are some thoughts.
Silver (and gold) have had big runs over the last year or so. If you look at the 1 year and 5 year chart for each (a decent place to track the price/see the chart is here -
Silver - Price - Chart - Historical Data - News), you see a 'rhino horn' formation where price is looking like it is going parabolic. In general, that is not the time to buy something after it has run up in price like that. In most cases it indicates that there will be a violent correction down in price at some point and a pattern like that usually indicates a time to sell something like at least 1/3 of what a person holds (ie take profit). That doesn't mean that price is done going up, but that it has just extended too much, too fast to be sustainable and usually corrects to start to build a base at a lower in price in which to start rising again. If you look at what technical analysis people (just looking at the charts for patterns and indicators, etc) are saying, they are saying that silver is at a strong sell price technically and likely doesn't have much more upside before it corrects.
Now, an exception to this talk about what a lot of technical only analysis people are saying is the massive and very long term 'cup and handle' pattern silver had formed and where the price broke out from. See this post of mine -
Silver goes ballistic and shakes the financial system - where I mention it and also possibly a bigger, longer pattern for silver. Some say due to the 'power' and long term nature of the pattern that silver has more upside.
Now, beside technical analysis people talk about the fundamentals of something or fundamental analysis. Many of the post here in this thread and links shared talk about this for silver, such as my post (link provided above). Despite what the technical analysis (the charts and indicators) might be saying about something like silver, the fundamentals say it could go higher, even much higher before there is any kind of meaningful, bigger correction. And then, that might be just temporary before it goes even higher on the longer term time frame.
I personally think the fundamentals will continue to drive the silver price higher for at least a time, but it isn't often something just goes up parabolic (rhino horn) on the charts on and on and on... Maybe just buy one or two coins from somewhere and then see what happens. That way you might have some buy-in in terms of learning more about the topic without committing a lot of money.