Looked on Amazon, they have various ones under $30 (with instructions in Chinese but will look for the You Tube videos LQM!!) it is not in the product descriptions and only one review mentions one phone not having that, so do not know if ALL cheaper ones do not have it. Also would like the lost and found alarms if they have it.
You're not likely to get a watch with LTE capability for under $30, or even "CHEAP". If you're just looking for a watch to link to your cell phone, there are many options. Some cost more than others and the old cliché of "you get what you pay for" comes into play.