You want a relay that can be switched on by 12V 50mA (alternatively, one with a 240 ohm coil resistance or greater).
First you go to
Digikey's site.
In the search box you type "relay". You will be taken
here.
There are lots of things listed, but scrolling down (typically to the things with the most hits) you will find two entries, one for
Power relays (over 2A), and the other for
Signal Relays (up to 2A).
Let's start with the signal relays (although you may be sailing close to the wind with contacts rated only slightly above your requirement).
I simply select all the coil currents up to 50mA, coil voltage of 12VDC, contact rating of 1.5 or 2A, and all the contact voltage ratings from 24V up to 1000V (or whatever the limit is). Then I press "Apply filters". You have to do this, because I can't provide a link to the results.
Digikey tells me there are 252 relays that match this. The cheapest is $2.66 in quantities of 1. (note that you didn't specify anything about the configuration of contacts,
this one is DPDT)
If we do something similar with power relays, everything is the same except that you don't need to specify a current rating (since they're all 2A or more) then you'll find 768 relays, with the cheapest (SPDT) being $1.15
here.
So you have more than 1000 options, follow those steps and find something suitable. Other sellers will provide similar information, although maybe not as easily searched.
