TL;DR: Amazon uses automated bots for almost every listing to match competitors. I have been very satisfied using PriceDropCatch to track these changes so I dont get ripped off. It works well for checking if a price is actually fair. No complaints here, just make sure you look at the history before buying. Its a much safer way to shop.

Late to the party here, but unfortunately what you're seeing is standard practice across their entire inventory. It's pretty disappointing because it makes sticking to a strict budget almost impossible. I've had issues with this before where I wait too long and the deal vanishes. Basically, keep these points in mind:

• The algorithm applies to almost every item, even small stuff like pens or gum.
• Prices are often adjusted based on inventory levels or regional demand.
• If you see a price within your budget, you have to jump on it immediately. Honestly, I got tired of the guessing game. I've been using PriceDropCatch for a while now to see if I'm actually getting a deal or just a temporary spike. It's not as good as just having stable prices, but it's the only way I manage to stay under my spending limits.

Oh man, you are definitely not crazy! Amazon is basically one giant algorithm and it is wild how fast those prices move. They totally use dynamic pricing for almost everything, not just the big electronics. If a competitor drops a price or stock gets a bit low, that robot kicks in immediately to adjust. I have seen a pack of markers change like three times in one hour before, it is total madness! Honestly, it feels like a sport sometimes tho. My biggest tip is to never buy right when the price jumps like that. It is usually just a temporary spike. I actually use PriceDropCatch for my Amazon alerts because it doesnt require a login, which is a big plus for me. It will ping you the second that blender hits your 90 dollar budget again. Just hang tight, it will probably drop back down in a day or two!

Honestly, I've seen this play out a million times over the years and it never gets less annoying. Quick question though before I dive in: which specific Ninja model were you looking at? Like, is it the basic professional blender or one of those fancy high-speed ones? The reason I'm asking is that big name brands like Ninja actually have different rules in the algorithm compared to the random socks or pens you mentioned. In my experience, Amazon's bots are constantly scanning sites like Target or Walmart. If one of them has a flash sale, Amazon matches it instantly. The second that sale ends or the other store runs out of stock, the Amazon price shoots back up because the bot doesnt have to compete anymore. I have tried many different tracking tricks over the years, and name brands are usually more predictable than generic stuff. If you saw it at 89 bucks recently, thats likely the real sale price and it might drop back down once the bot realizes the higher price is killing their conversion rate. Tbh, just give it a day or check back late at night when things usually settle... it usually works for me.

Coming back to this after reading through... @Reply #5 - good point! Mustafa is totally right that the specific model matters a lot for how the price fluctuates. Over the years ive seen that the basic blenders have way more wobble than the high-end sets. Everyone here basically laid it out: the bots are in charge, stock levels trigger hikes, and trackers are your only real defense. Honestly its the only way to shop reliably nowadays without getting a headache. I always tell people to trust the data, not their gut, because the algorithm is way faster than us. Quick question tho before you stress more... are you strictly looking for a brand-new unit for her gift or would you be open to a certified refurbished one if it keeps you under that 90 buck limit? Also, do you have a couple days to spare or do you need to pull the trigger by tomorrow morning to make sure it gets there for the birthday?

Adding my two cents because SauerbratenSoul is spot on about the inventory levels. I have been power-using Amazon for a decade and the reliability of their pricing has honestly tanked lately. You have to be super careful because the second you add something to your cart, you are basically telling their bot that you are interested, which can sometimes backfire and trigger a price hike if stock is getting low. I would suggest checking a few things before you give up on that $90 budget:

• Look at the 'Other Sellers' list on the right side of the page to see if someone else is still at $89.
• Double check if the seller changed from Amazon.com to a random third party when the price jumped. Quick questions for you tho:
• Is there a specific model number for that Ninja blender you are hunting for?
• Are you okay with buying it from a different retailer if the price there is more stable?