This is really the only extension I know of that helps with this aspect of comparison shopping - plenty of extensions will compare the price of a specific item across retailers but before Lustre I was stuck relying on Amazon's recommendations (most of which are sponsored brands only) to find other items similar to the one I'm looking at that I might want instead.

Enter Lustre.ai. Basically, Lustre aggregates reviews from a wide range of online sources as well as current selling prices for an item across major online retailers, and uses that info to rate how good of a deal it thinks each item is. It breaks items down into categories, so it can tell you what similarly prices items in that category it thinks might be a better deal right now. You see badges next to some items as you browse Amazon with one word summaries like "decent" or "excellent" to make it easy to pick out the most promising listings as you search, and clicking on that badge (or the extension icon while on the item's product page) will show you more info. Click through from the popup box to lustre's website and you can look at all the items it has rated in that product category, sorted by price, with category-specific filtering options to help narrow down the selection to items that are relevant to you. There are also links to the sources it relies on for ratings if you want to read what professional reviewers have to say about a product for yourself. It will also give special labels like "cheapest worth buying" or "best for most people" on specific items to further help the standout deals, well, stand out :P

The two standout features IMO that set this apart from websites that try to do similar things (aside from being more convenient as an extension that integrates into Amazon and other retail sites directly) are 1. the thing I already mentioned about recognizing when an item is on sale and factoring that price reduction into its ratings, a must have feature in this era of neverending streams of flash sales and holiday promos, and 2. the hand tuning that goes into each product category and tells the algorithm which reviewers should be given the most weight based on how in-depth their reviews are and whether this is a product category they specialize in or just one of a laundry list of things they review. A site specializing in cell phones and related accessories might have great reviews of phone cases and phones themselves but Wirecutter or RTINGS are better sources for reviewing high end headphones. Lustre knows this and weights them accordingly on a per product category basis.

One very minor gripe to mention: I assume Best Buy must sponsor them or something because they will very frequently show products that are the same price on Amazon and Best Buy but show the exact Best Buy price while rounding Amazon's up to a round dollar figure to make it look like BB is marginally cheaper. Like I said, very minor gripe, but it does this so often that you can't help but notice before long and it's the one and only thing that has given me even a hint of doubt as to their objectivity. On its own it's a non-issue IMO but if it gets more egregious and starts "accidentally" not picking up Amazon price reductions or quietly de-emphasizing products that BB doesn't carry or isn't price competitive on, that would be unfortunate to say the least. I see no evidence of anything like that so far though, it may not even be a sponsorship thing maybe it's just a slight inconsistency in how Lustre's devs coded the scraper that gathers up to date pricing info for products in a way that just happens to favor BB. And if BB is paying to keep the lights on in exchange for getting its buy link first and having it say 99.99 instead of 100, I'm glad BB thinks that's worth paying for and I would take that deal in Lustre's place in a heartbeat :P Amazon is the first buy button on the majority of products, as expected given that they are usually the cheapest or tied for the cheapest with other retailers who price match them.

TL;DR: ever buy stuff online? Ever have trouble deciding which stuff is the best deal to buy? Wish you had something more trustworthy than Amazon pushing its sponsored brands as helpful suggestions to find competing products? Install Lustre.

Lustre makes the difference between buying the marketing and buying the goods. I get enough reviews to know I'm getting the best products and in the place I'm shopping.

Non-intrusive, attractive interface that has come in very useful as a review aggregation tool for over 10 purchases I've made in the last few months, both big and small! Especially for an indecisive schmuck like me, helps a lot

Great extension that can make shopping so much easier for those of us with decision paralysis. I've made several confident and informed purchases with Lustre.ai and it saved me what might possibly be hours of worrying and research just by narrowing down my options and giving me quality ratings at a glance.

At this early stage, there is not always a category yet for what I'm looking for, and some of the ratings are a little insubstantial - e.g. when a product is merely listed but not particularly recommended in an article.

Kudos to the devs - after reporting a bug, a fix was released a day later.