This is a good question without a lot of public answers on the internet so I figured I could help.
Why The 999 Trick Won’t Work
Some sellers restrict the number of items a person can buy. There are a number of reasons to do this, but the primary reason is probably to prevent having your inventory cleared out through a misconfigured coupon code.
The second reason is to keep your competitors from knowing when you’re running out of stock. There are a number of things you can do to take advantage of your competitors stockouts, we’ll save that for a later post, but for right now I’ll explain how to fairly accurately track the inventory of an item. that has this blocked using it’s BSR.
What is BSR, in this context?
While no one knows exactly how Amazon’s ranking method works, it’s safe to say that one of the strongest determining factors is sales per day.
So if an item with a BSR (Best Seller Rank) of 10 sells 20 per day, and an item with a BSR of 20 sells 10 per day, it’s safe to assume that an item with a BSR of 15 sells somewhere between 10 and 20 per day.
However it’s a little more specific than that, because Amazon calculates this number _per_ category. That means an item with a Best Seller Rank of 20 in PETS might sell far more than an item with a BSR of 20 in “Industrial & Science” because it’s like 99% more fun to buy a dog a pet than it is to buy a pocket protector. That’s science.
Because of the “category specific” ranking you can use the category neighbors of an item to find the rank.
Let’s use an example
This Zilla Premium Reflector Dome has a BSR of 818 in Pets. Lets pretend the 999 trick isn’t working.
What you would do is try to find a BSR of AROUND 818 in the Pet Department and track that item instead. You could either click on one of the sub category links or browse through the main category.
By browsing through the main category, using the extension we see that there’s an item with a BSR of 811 right above it.
And using the sales estimate for this item we can see that it appears to sell 1 – 2 more items per day on average.
By clicking *track* on this item, Amachete will automatically perform the 999 trick on this *neighboring* item every day, and we can use *that* items BSR/Sales per day to very accurately predict what the daily sales are for the heat lamp.
I hope that helps, Chris.