I bought an MTG 3000 like the following on eBay. It was less back then (they seem to have inflated in price).
it’s simple to use and gives repeatable results.
Note: it’s a great tool for someone “curious” about watch timing. Not a replacement for accurate timing devices used by professional watchmakers. Only get one if you won’t obsess over what you find, as it could ruin a good watch by exposing what is normally hidden.