Prisync is strong — but it's built for scale
Credit where it's due: Prisync is one of the most established competitor price-tracking tools, with a high review rating and deep features for large catalogs and aggressive repricing. If you're an enterprise running thousands of SKUs against dozens of competitors, it's a serious option.
The catch for most Shopify merchants is the entry point. Prisync is generally priced from around $99/mo and is trial-led rather than free. If you just want to keep an eye on a handful of specific competitors — and react fast when they move — that's a lot of tool and a lot of cost for the job.
PriceSentry is the right-sized alternative. You point it at the exact competitor product you care about, it re-checks every day, and it emails you the moment the price or stock changes. Start free with one product; pay $19/mo only when you're tracking more. Same core job, a fraction of the cost, and a person answers when you need help.