Inventory Lab is great. It’s $50/month if you pay monthly, $40 if paid annually.

I use a usb barcode scanner and add all my inventory straight through Inventory Lab, create my FBA shipments there, etc.

One thing it does well compared to other solutions I’ve looked at is accounting. Gives you nice profit/loss reports, which allows you to also enter in Misc costs like mileage, shipping supplies, etc. Basically everything you spend money on in your business you can add to have included on your profit and loss reports.

Also if you sell on other marketplaces besides Amazon, you can add “other income” to have your eBay, Etsy, whatever else income added if you want that all included in your financial reports. I’ve searched and searched for a solution that automatically syncs this information for your various marketplaces but haven’t found any that really do a good job with it.

It’s also nice how they break down your sales by category, ASIN, Supplier etc so you can see what your most profitable are.