I'm winding down my Amazon FBA side hustle as I don't really have even the minimal time it takes. Two jobs and five kids doesn't leave much room for starting and running a business.
However, I'm going to provide a decent opportunity for retail/online arbitrage for anyone who wants to jump on it. If you take advantage of this I ask that you use the referral link in my signature and get yourself a free share of stock (as well as a free share for me) by signing up for the Robinhood app. Obviously if multiple people take advantage of this at the same time the arbitrage opportunity will eventually go away but for someone who's looking to move up from one-off clearance items this is a decent example of what's out there.
I found a brand of shampoo and conditioner that is selling alright on Amazon, BRÖÖ. They have four different varieties of shampoo and conditioner (plus some other related beauty products). The sets of these have sales ranks averaging around 60,000 to 100,000 which translate to monthly sales of 15-30 per month or so. A couple of these are carried at Walmart's and sell for around $6-7 per bottle. I had been selling all four as bundles and doing pretty well for a few months but I had a bunch of issues because I did not include a label/sticker marking them "sold as set". Because of this, when I sent a large shipment in to the Baltimore warehouse they opened up the poly bags I had packaged them in and 10+ orders were fulfilled with just a single shampoor or conditioner instead of the set. Amazon reimbursed me for some but still, I messed up by not including that label and had to spend a lot of time getting negative feedback removed and responding to complaints.
Since then the most popular variety has seen a bunch of other sellers jump on the listing and the price has been driven down to breakeven. However, one of the varities is still selling about 20 units per month at around $30 with just a couple of other sellers - none of whom have more than a handful of units in stock.
https://www.amazon.com/dp/B01DUY3M2UHere is a link to an online seller
https://www.iherb.com/pr/BR-Invigorating-Shampoo-Malted-Mint-8-5-fl-oz-250-ml/66022 and
https://www.iherb.com/pr/BR-Invigorating-Conditioner-Malted-Mint-8-5-fl-oz-250-ml/66023 The price drops to $6.29 each if you order a dozen or more. They offer $5 off on your first order with coupon code APPS2018. They are also offering a coupon code for 11% off for the next couple of days (referral link)
https://www.iherb.com/?pcode=WCELEVEN&rcode=AHP8153 So if you were to order a dozen of each with that 11% off and free shipping your cost would be a little more than $11 per bundle. You will also need poly bags to put the shampoo and conditioner in (plus the sold as set label/sticker). I purchased this set
https://www.amazon.com/Clear-Poly-Combo-Suffocation-Warning/dp/B01DLIRW8K and the smallest 6"x9" bags worked fine
https://www.amazon.com/Clear-Poly-Combo-Suffocation-Warning/dp/B01ESFYDSC?th=1 You will also need to print labels to put over the UPC barcodes and I would recommend a single label on one barcode with your FNSKU and a second blank label over the other barcode. I think because I put FNSKU barcodes on each in one shipment it caused the warehouse workers to treat it as two items instead of one.
So with labels and poly bags being only pennies each your cost of goods sold will be less than $12. If you ship this into Amazon FBA your inbound shipping will probably be around $0.50 per unit bringing your total COGS to about $12. The fulfillment costs at a price point of $30 are a bit more than $9. So, if you can sell this bundle for $30 with a total cost of about $21-22 your profit is about $8-9. As I said, this particular variety is selling about 20 units per month according to keepa.com which means a potential profit of $170 a month give or take.
Good luck.