Ok, so far, all I've seen is a lot of guessing about what will work for the OP. Let's do a bit of math to figure it all out.
The OP says that he has 1 volt at 30 ma available when he wants the relay to turn on. Let's just look at a typical low power transistor datasheet. Let's start with the venerable 2N2222A. It's available from many distributors such as Mouser and Digikey.
The datasheet says that it can handle 600ma of collector cuurrent. Typical 5V relays of this nature have a coil resistance of 160 - 200 ohms. So, the collector current the transistor will have to handle is roughly 30ma or less. Not a problem for our transistor.
Now. we need to figure out how much current the base needs in order to switch the transistor into saturation. Typical Vbe for a silicon transistor at turnon will be about 0.65 volts. So, if we have 1V to drive it with, we know that we have adequate voltage to turn the base-emitter junction on (1V > 0.65V).
Now, how much current will we need into the base? From the datasheet, we see that with a collector current of about 30ma, the transistor has a DC current gain (Hfe) of about 100. That means that if we need a collector current of 30ma, the base current will have to be .03ma/100 = .0003ma, or 300ua. The base-emitter voltage is 0.65, so the voltage that the resistor needs to drop is 1-0.65 = 0.35V. So, the base limiting resistor will need to be approx 0.35V/0.3ma, or 1.2K. The 100K resistor is there to prevent collector-base leakage current from turning the transistor on.
Now, we know that the 1V input can turn our transistor on with enough gain to energize the relay. The only thing remaining is to latch the relay. See the diagram below for that. The OP will have to get a double-pole relay in order to latch it on. Otherwise, we would have to build a bistable latch (flip-flop) in order for it to work. Simpler to get the appropriate relay.
View attachment 50091
Cheers,
Dave M