I've had luck with junkyard injectors and rail assemblies for imports. They
can be a little ruff getting the screws loose, I find vice grips to be
handy on getting them loose.

To check the injectors you can use a long screwdriver and hold it tip
against the injector as the engine is running and press your ear against
the handle's end to listen for the clicking as it travels through the
tool. Listen to all 4 injectors and the culprit will be the oddball one.
Usually with a very dull tick.

You can also use a volt meter to check the resistance on the injectors,
they should all be very close to each other, within 0.2 ohms. Sorry, don't
recall the exact measurement.

Although, this problem could be something else, such as a vacuum leak,
stopped up filters, but these would be consistent and show up immediately.
Could also be a bad IAC/EACV which controls the idle.

I can't say if its safe to drive though, and 100 bucks is about normal for
new injectors.

Best of Luck